Bipolar Disorder with Seasonal Pattern

🧠 Overview — What is Bipolar Disorder with Seasonal Pattern?

Bipolar Disorder with Seasonal Pattern is not a new disorder, but an important specifier that is added after the diagnosis of Bipolar I or Bipolar II to indicate that the patient’s depressive episodes or (hypo)manic episodes recur in a seasonal pattern, consistently, over many consecutive years, to the point that a clear pattern can be detected. This is different from “feeling down just because it’s winter” in a general sense, because in this case, the symptoms are severe enough to reach the level of an episode and significantly impair real-life functioning.

The history of this specifier began with its use to describe Major Depressive Disorder (MDD), especially in patients who experience severe depressive symptoms during winter. Later, DSM-5 expanded it to cover manic/hypomanic episodes in bipolar disorder, because research found that a subset of bipolar patients “bounce up and crash down” in accordance with the seasons in a systematic way—for example, crashing into depression in winter but becoming unusually energetic and activated in spring or summer.

Research indicates that 15–25% of bipolar patients have a detectable seasonal pattern, especially in terms of depressive episodes. This makes the diagnosis of this specifier highly important for treatment planning and preventing future relapses. Once the high-risk seasons are known, clinicians can create a “pre-season plan” involving medication, sleep scheduling, and lifestyle adjustments with greater precision than in bipolar cases without a clear seasonal component.

The most common patterns can broadly be divided into two main types:

• Depression predominating in late autumn–winter, with improvement in spring–summer

• Elevation/activation (hypomania/mania) in spring–summer, followed by remission during the cooler seasons or winter

Some cases show mixed forms or have additional peaks during transitional seasons, such as autumn or early winter, when daylight decreases rapidly.

The relationship between mood and seasons does not arise from weather alone but is driven by the circadian rhythm system, light exposure, melatonin, serotonin, and changes in the brain’s “biological clock.” Evidence from chronobiology research shows that many bipolar patients are particularly sensitive to changes in day–night length.

In addition, ICD-11 includes a specific code, 6A80.4 – Seasonal pattern of mood episode onset, to specify that the onset of mood episodes in a patient truly follows a seasonal pattern. This specifier can be used alongside Bipolar I, Bipolar II, or even recurrent depressive disorder, which means seasonality is formally recognized in both DSM and ICD.

Overall, this specifier helps us understand the rhythmicity and cyclical nature of mood in bipolar patients—mood does not fluctuate randomly, but has “its own seasons.” Once this rhythm is recognized, treatment, mood management, and life planning for patients can be done with much more precision and strategic foresight. For example: adjusting mood stabilizers before entering high-risk seasons, using IPSRT to stabilize sleep–wake times, or increasing sunlight exposure/light therapy carefully during seasons with a high risk of depression.

In one sentence:
It is a form of bipolar disorder in which mood rises and falls in a systematic seasonal pattern, grounded in biology, and it is crucial for evaluating the course of the illness and preventing future relapses over the long term.

💥 Core Symptoms — Main Symptom Profile

The key idea is:

The symptoms of Bipolar Disorder with Seasonal Pattern are not different from typical bipolar disorder in terms of the types of episodes (mania, hypomania, depression).
What differs is the timing and the recurrent seasonal pattern in which episodes return in a structured way.

From the patient’s perspective, it can feel like living on a “seasonal roller coaster,” for example:

• As late rainy season–early cool season approaches → they already know they’re about to start crashing.

• When hot season or summer arrives → it feels like the emotional engine turns on by itself: elevated, driven, with multiple projects and nonstop activity.

1) Pattern of Depressive Episodes (Seasonal Depressive Episodes)

1. Occurring in the same season repeatedly over many years

The core of a seasonal depressive episode is:

“It’s not just a random episode of feeling down in winter this year only; it’s becoming depressed every year, around the same time period.”

This pattern is especially clear in latitudes that have winters or short, dark days.

In tropical countries like ours, the pattern may align with “periods of prolonged rain and reduced sunlight” or “intense end-of-year stress with an underlying biological component.”

2. Typical depressive features (similar to SAD)
Most cases resemble Seasonal Affective Disorder (SAD) of the winter-type, including:

• Excessive sleepiness / drowsiness / sleeping much more than usual (hypersomnia)
• Waking up still feeling “drained,” as if sleep is never enough, even after long hours
• Craving carbohydrates, sweets, and high-carb foods such as bread, cakes, and fried snacks
• Gaining weight easily during the depressive season
• Feeling exhausted (fatigue), both physically and mentally, as if everything takes too much effort
• Loss of motivation (amotivation); work feels impossible, with thoughts like “everything is too heavy”
• Decreased concentration, slowed thinking, and difficulty making even small decisions
• Sad mood, emptiness, feelings of worthlessness and disappointment in oneself
• Suicidal thoughts or a desire to disappear, even if no concrete plan has been formed

3. “Dropping and staying stuck” for that entire season

• Depressive episodes often last for several weeks to months.

• In other seasons, the patient may improve markedly—some return to “almost 100% normal,” or swing to the opposite extreme with hypomania.

• This contrast leads some patients to say:
  “It feels like I have two versions of my life depending on the season—one where I’m myself, and another where it’s like all my energy has been drained.”

4. Symptoms are often more “atypical” than melancholic

• This differs from melancholic depression (early morning awakening, insomnia, poor appetite, weight loss).

• Winter-type seasonal patterns more often show:
• Sleeping more, eating more, gaining weight
• Hypersensitivity to rejection from others
• Mood fluctuating considerably based on relationships and environment

5. Impact on daily functioning

• Work/school performance clearly declines during high-risk seasons.

• Patients may resign, change jobs, or drop out of school repeatedly during the same period each year.

• Relationships become strained because partners or people around them may feel that:

“Whenever this season comes, they turn into a different person.”

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2) Pattern of (Hypo)mania / Mania

For some individuals, the seasonal axis lies more on the “elevated/over-activated” side than on the depressive side.

1. Seasons where (hypo)mania is commonly seen

Many studies show that (hypo)mania/mania tends to peak in:

• Spring
• Or summer (when there is abundant light and long days)

In tropical climates, a pattern may appear where:

• As bright, long days begin (longer daylight, stronger sun), the patient’s mood begins to climb.

2. Core features of (hypo)mania / mania (classic profile)

• Abnormally elevated mood / euphoria / excessive confidence, or in some cases, marked irritability
• Very little sleep (e.g., 3–4 hours) yet feeling “ready to go” and not tired
• Speaking very rapidly, racing thoughts, a flood of ideas, talking almost nonstop while others struggle to keep up
• Intense drive to start many new projects at the same time
• Excessive spending—shopping without considering consequences, risky investments without risk evaluation
• Increased risky behaviors related to sex, gambling, speeding, or substance use
• Grandiosity, such as believing one has a special global mission or abilities far beyond reality
• In very severe mania, psychotic symptoms may appear, such as delusions or hallucinations

3. “Up-season vs down-season”

In some patients, the pattern is very clear:

• One season = depressive
• Another season = elevated (hypo/mania)

As a result, the yearly course looks like a “seasonal sine wave,” which has major implications for treatment planning.

Some patients even “secretly enjoy” their hypomanic periods because they feel productive, creative, and socially skilled, which can make them reluctant to take mood-stabilizing medication → increasing the risk of a crash afterwards.

4. Mixed Symptoms with seasonality

Not everyone’s mood divides neatly into separate “up” and “down” states.

Some cases show mixed features, such as:

• Insomnia, racing thoughts, high activation—but internally feeling sad, hopeless, and suicidal.

Mixed states with seasonality make each episode “more dangerous,” because the combination of energy + dark thoughts → greatly increases the risk of self-harm.

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3) Other Key Shared Characteristics

1. Impact on work / education / relationships

In the problematic season (whether depressive or elevated, depending on the person):

• Work collapses, deadlines are missed
• They receive criticism or warnings, relationships become tense

But once the season passes, patients often “do well again,” which confuses people around them and leads to misinterpretations such as “they’re just lazy sometimes,” which is not accurate.

2. Rapid Cycling + Seasonal Pattern

Some individuals experience both rapid cycling (≥ 4 episodes per year) and additional seasonal peaks.

• More common in women
• Associated with higher risk of chronic depression, poorer response to some medications, and a more complex course

People in this group may feel like their life never has a truly “stable” period throughout the year.

3. Increased suicidality during seasonal depressive episodes

During seasonal depressive episodes, suicidal thoughts or self-harm ideation often spike.

If it’s a mixed episode with seasonality, the risk is even higher because hopelessness and energy co-exist → there is both desire and capacity to act.

4. Common comorbidities

• Anxiety disorders: generalized anxiety, panic disorder, GAD

• Eating disorders: some overeat and gain weight seasonally, hate their body, and enter/exit diet cycles

• ADHD or issues with attention/planning life:
• These individuals already struggle with routine.
• Adding seasonality on top → life management becomes even more chaotic.

Summary of this section:
The core symptoms of Bipolar Disorder with Seasonal Pattern are those of full-blown bipolar disorder, but with a very clear “seasonal signature”—there are seasons where depression is consistently severe, seasons where elevation is more frequent, or both alternating every year. Looking back at a timeline, one can see that this person’s mood ups and downs are systematically tied to specific times of the year.

📋 Diagnostic Criteria — Diagnostic Framework

In DSM-5 / DSM-5-TR, the phrase “with seasonal pattern” is a specifier that can be attached to mood disorders such as:

• Major Depressive Disorder
• Bipolar I / Bipolar II

Clinicians are not just looking for “feeling down in winter,” but for the following structural criteria:

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1) A consistent temporal relationship

The primary criterion:

Depressive episodes or (hypo)manic/mania episodes must occur during the same time period of the year, consistently.

In clinical language, for example:

• “Every late rainy season–early cool season, the patient begins to feel themselves crashing, leading to a full depressive episode between November and January.”
• “Every late March–April, the patient begins sleeping less, talking more, taking on many projects, and regularly enters a hypomanic or manic state around the Songkran period.”

Clinicians will try to differentiate whether:

• This pattern is tied to the natural cycle of light–weather–season,

or

• It is tied to recurring yearly life events (e.g., year-end financial stress, quarterly reports, exam season, etc.)

If it is only the latter (for instance: “I get depressed every December because year-end financial stress is overwhelming”), it will not be classified as a seasonal pattern in the strict biological sense.

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2) Remission also follows a seasonal pattern

It’s not only the “onset of symptoms” that needs to be seasonal; the “timing of improvement” must also follow a stable seasonal pattern.

For example:

• Depressive in winter, then gradually recovering in summer until near-normal mood returns.
• Elevated in summer, then stabilizing as the rainy season approaches.

This helps distinguish seasonal pattern from depression that persists all year but simply becomes worse during one particular season.

In other words:

We need to see a “wave form” of mood that rises and falls with the seasons, not just “falling” and then staying flat all year.

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3) The pattern must persist for at least 2 consecutive years

This is a very important “screening gate.”

DSM-5 specifies that for at least 2 consecutive years:

• There must be depressive/elevated episodes that meet full episode criteria occurring in the same season reliably.

And during those 2 years:

• There should not be frequent major episodes that occur outside the usual season and disrupt the ability to recognize the pattern.

Furthermore, across the entire lifetime course:

• The number of episodes fitting the seasonal pattern should be greater than the number of episodes occurring randomly throughout the year.

Example comparison:

• Patient A:
• In the past 5 years, has had depressive episodes every winter (4 times), with no major depressive episodes outside winter → clearly fits a seasonal pattern.

• Patient B:
• In the past 10 years, has had 7 depressive episodes scattered throughout the year, 2 in winter, 2 in summer, etc. → the pattern is not consistent enough to be called seasonal.

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4) Not fully explained by environmental/social factors

Clinicians will ask extensively about this, because it’s necessary to differentiate:

• A corporate employee whose workload is extremely heavy every year-end → gets depressed every December due to deadlines and financial pressure → this is a psychosocial seasonal pattern.
• A farmer who is stressed every dry season because income drops → depressed every dry season due to life circumstances.

In theory, DSM aims to capture seasonal patterns driven primarily by biology/circadian/light.
In real life, it’s often a blend of biology + life stress.

→ Therefore, clinicians rely on their clinical judgment to decide which driver is dominant.

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5) In the bipolar context: the primary diagnosis comes first

Another crucial point:

• A clear diagnosis must first be made as:
• Bipolar I, or
• Bipolar II
• Using full DSM-5 criteria regarding number of symptoms, duration, and impact on daily functioning.

Only then do clinicians evaluate whether the course of the disorder has a “with seasonal pattern” specifier.

Thus, this specifier

• is not meant to say, “You have bipolar because of the seasons,”
• but rather to say,

“Among all the episodes you’ve had, your bipolar illness shows a seasonal pattern.”

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6) Use of auxiliary tools such as SPAQ / Mood Charts

In practice, clinicians may use:

• SPAQ (Seasonal Pattern Assessment Questionnaire)
• To assess the extent to which mood, energy, sleep, and behavior change with seasons.
• To explore how much the patient themselves perceive seasonal impact.

• Mood Chart / Life Chart
• Documenting a timeline of mood across the year, together with important life events.
• If tracked over many years → clear seasonal waves may emerge.

These tools do not replace DSM criteria, but they help:

• Patients see their own pattern clearly.
• Clinicians obtain quantitative and temporal data (month-by-month) to support diagnosis.

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7) View from ICD-11

In ICD-11 there is a specifier:

“with seasonal pattern of mood episode onset”

The logic is similar to DSM:

• The onset of mood episodes shows a clear seasonal association.
• It can be used with Bipolar I, Bipolar II, or recurrent depressive disorder.

At the international level (DSM and ICD),
seasons are now recognized as an important “course modifier” for mood disorders, not just a minor detail.

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8) Distinguishing from “just disliking certain seasons”

This is crucial for general readers:

• Not everyone who “dislikes winter/rainy season” has the seasonal specifier.

Key criteria:

• There must be depressive or elevated episodes at the episode level (significantly impairing work, functioning, and relationships).
• The pattern must be clearly present over multiple years.
• It is not just “feeling a bit low or irritable” in some seasons.

If it is simply feeling more sleepy or a bit lazier in certain seasons → it might fall into the “winter blues” or “subsyndromal SAD” zone, which is milder and does not meet full episode criteria.

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9) Using the specifier for treatment planning and prevention

Once a clinician labels a case as Bipolar Disorder with Seasonal Pattern,
treatment planning can shift from reactive to proactive. For example:

• 1–2 months before the high-risk season:
• Review medications
• Adjust mood stabilizer doses
• Plan sleep, light exposure, and workload

• Increase the frequency of follow-up visits before and during high-risk seasons.

• Educate patients and families to recognize early warning signs specific to their seasonal pattern.

All of this becomes possible because the seasonal pattern has been systematically identified from the beginning.

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10) A one-sentence DSM-style summary

If we were to summarize the Diagnostic Criteria in the shortest form:

“In someone who already has bipolar disorder, if their mood rises and falls into depressive/elevated episodes that appear and remit during the same time of year, consistently for at least 2 years, and this pattern is more prominent than random relapses, we call it Bipolar Disorder with Seasonal Pattern.”

🧩 Subtypes or Specifiers — Common Clinical Patterns

There are no official subtypes that create separate diagnoses, but in clinical practice, we frequently see the following patterns:

1. Winter-Depression / Spring–Summer Hypomania Pattern

• Depression predominates in winter: resembling classic SAD.
• (Hypo)mania predominates in spring or summer.
• This is the most frequently reported pattern in bipolar disorder with seasonal pattern. PubMed Central+1

2. Summer-Depression / Fall–Winter Hypomania Pattern
Some patients show the reverse:

• Depression during summer (some studies report an additional depressive peak in summer). BioMed Central+1
• Followed by elevation during cooler seasons or seasonal transitions.

This is often misinterpreted as “just summer SAD” if clinicians do not carefully explore a history of hypomania.

3. Depressive-Dominant vs (Hypo)Manic-Dominant Course

• Some patients have only seasonal depressive episodes, with almost no prominent mania, making the picture resemble MDD with seasonal pattern.
• Others have frequent seasonal hypomania with relatively minor depression—differentiation requires detailed history and long-term course observation.

4. Rapid Cycling + Seasonal Pattern
Women and patients with rapid cycling are more likely to exhibit seasonal patterns.

• The course becomes very complicated: frequent episodes + seasonal peaks. PubMed Central+2 PubMed+2

5. ICD-11 Specifier Combination
In ICD-11, clinicians can stack multiple specifiers, for example:

Bipolar type I disorder, current episode hypomanic, with seasonal pattern, with prominent anxiety, with rapid cycling, with melancholia … PubMed Central+1

When writing content, you can spin this line into multiple sub-posts, such as:

• “Winter-Depression Pattern in Bipolar II”
• “Rapid-Cycling + Seasonal Pattern: Why is it so hard to treat?”

🧬 Brain & Neurobiology — Brain and Biological Mechanisms Involved

Bipolar Disorder with Seasonal Pattern is one of the clearest examples proving that:

“Human mood does not fluctuate randomly; it is rooted in time systems, light, hormones, and genes that govern everyday life.”

This topic is the core of understanding this disorder. If you understand circadian and light biology in detail, you will immediately see why some patients “elevate when days are long and crash when days are short,” and why seasons can hit the mood circuits so strongly in bipolar individuals.

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🧠 1) Circadian Rhythm and the Role of the SCN (Suprachiasmatic Nucleus)

The SCN = the master clock of the brain.
Located in the hypothalamus, with about 20,000 neurons, it synchronizes all life rhythms, such as:

• Sleep–wake timing
• Melatonin secretion
• Cortisol secretion
• Body temperature
• Hunger–satiety
• Alertness for attention and executive functions

This is crucial, because bipolar disorder is inherently a condition in which the circadian rhythm is already compromised.
When seasons strike this system, mood swings become more intense.

Pathway of light into the brain:

• Light enters the eye.
• It is detected by intrinsically photosensitive retinal ganglion cells (ipRGCs).
• Signals are sent directly to the SCN.
• The SCN adjusts pineal gland activity to start/stop melatonin secretion.

In a Winter-type pattern:

• Shorter days → the SCN receives less light → melatonin secretion is prolonged → the “sleepiness cycle” becomes longer.
• Bipolar patients with this pattern are often more sensitive to changes in light than the general population.

In a Spring/Summer Mania-type pattern:

• Longer days → melatonin secretion is reduced → the arousal system is heightened.
• Combined with a dopamine system that is easily activated in bipolar disorder → hypomania/mania flares up more easily.

Summary:
Seasonality = a powerful external zeitgeber for individuals whose circadian system is already fragile.

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🧬 2) Clock Genes — CLOCK, BMAL1, PER, CRY and the Genetic Cycle

The circadian system is not only the SCN. There is also a large “genetic clockwork” within almost every cell in the body, called the molecular clockwork system.

Key gene families include:

• CLOCK / BMAL1 → switch the cellular cycle on.
• PER / CRY → switch it off in a 24-hour loop.
• REV-ERB / ROR → modulate signal amplitude.

Recent studies show that:

• Many bipolar patients have polymorphisms in CLOCK and BMAL1.

• These variants can cause:
• The genetic cycle to run “too fast or too slow.”
• Difficulty resetting.
• Difficulty synchronizing when seasons change.

Some research suggests direct links such as:

• CLOCK gene variants → increased risk of hypomania.
• PER3 variants → difficulty waking in winter and increased vulnerability to depression.

Individuals with pronounced CLOCK dysregulation often respond better to IPSRT and mood stabilizers than to antidepressants.

In the simplest terms:

The genetic clock in some bipolar patients “runs off-beat from the start,” and when seasons strike, their mood swings in a patterned way.

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🌙 3) Melatonin System — The “Darkness Hormone”

Melatonin is the hormone that tells the brain “it’s time to shut down.”

Seasons influence melatonin directly:

• Winter = more darkness → melatonin secretion is prolonged.
• Summer = more daylight → melatonin secretion is shortened.

In bipolar disorder:

• Melatonin cycles are often already abnormally elongated or shortened.
• Seasonal changes further derail the timeline.

Studies in bipolar patients with a seasonal pattern find:

• Melatonin onset (time when sleepiness starts) often comes too early (winter-type).
• Melatonin offset (time when sleepiness wears off) often ends too late.

This makes patients feel “tired all day” during certain seasons.

Melatonin is also linked with the serotonin pathway → less light in certain seasons → lower serotonin → depressive episodes are triggered.

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☀️ 4) Serotonin – Reward, Calm, and Vitality System

Many studies indicate that serotonin levels decrease significantly in winter, because light regulates the serotonin transporter (SERT).

• More light = lower SERT → more serotonin remains in the synapse → better mood.
• Less light = higher SERT → more serotonin is reuptaken → mood drops.

In bipolar patients:

• The serotonin system is more fragile than in the general population.
• Even small decreases in light can cause more severe mood drops.
• Many patients describe it as: “When winter comes, it’s like someone turns the lights off in my brain.”

This helps explain why winter depression can be more severe in bipolar disorder than in typical MDD.

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⚡ 5) Dopamine — The System Directly Linked to Mania

Dopamine = energy + motivation + confidence + fast thinking.

Seasons influence dopamine through several mechanisms, such as:

• Changes in light exposure
• Reduced melatonin
• Adjustments in SCN output

Summer → more light → dopamine may rise more easily
→ This can lead to faster onset of hypomania/mania.

Some studies suggest that in bipolar patients who have mania tied to seasons, dopamine transporter (DAT) dysregulation is particularly pronounced.

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😴 6) Sleep–Mood Coupling — The “Sleep Fails = Mood Fails” Cycle

In bipolar disorder, sleep disturbance is not just a symptom; it is a trigger for episodes.

Seasons profoundly impact sleep:

• Short days and early darkness → the body assumes it should be sleepy.
• Long, bright days → the arousal rhythm is heightened.
• Shifts in sunrise/sunset times → the biological clock must constantly readjust.

In bipolar disorder:

• A shift of only 1–2 hours in sleep schedule can trigger hypomania.
• Sleeping more than 10 hours/day over time can trigger a depressive episode.

This is why Interpersonal and Social Rhythm Therapy (IPSRT) is very effective in this group.

We often call this phenomenon:

“Double hit”: circadian failure + sleep failure = mood failure on a greater scale.

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🧬 7) Molecular Seasonal Effects — Seasonal Changes in Gene Expression

Data from the UK Biobank and several genomic-scale studies show that:

• Seasons can change gene expression in thousands of genes, particularly those involved in:
• Immune function
• Stress response
• Biological clocks
• Monoamine synthesis

This means:

Seasons “switch on and off” certain gene sets in the body, and some individuals are more vulnerable to these shifts.

In bipolar patients:

• Winter = certain immune genes become active → cytokines increase → mood drops.
• Summer = genes related to arousal increase → dopamine becomes more active → mania can emerge.

All of this connects into a large, integrated biological system.

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🧩 Causes & Risk Factors — Why Some People Become Seasonally Sensitive Bipolar

This section summarizes why some people develop bipolar disorder that is extremely sensitive to seasons, while others—living in similar environments—do not.

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1. Genetics — Biological Vulnerability from Birth

Common genetic risk factors include:

• Family history of Bipolar Disorder
• Family history of Major Depressive Disorder with Seasonal Pattern
• Family history of SAD (Seasonal Affective Disorder)
• CLOCK/BMAL1 gene variants
• PER3 long allele
• Genes related to dopamine transporters
• Serotonin transporter gene (SERT)

Why is this important?
These genes regulate:

• Circadian rhythm
• Light sensitivity
• Sensitivity of the reward system
• Sleep mechanisms
• Serotonin synthesis

In simple terms:

These individuals are “born with more fragile brain clocks,” so when seasons hit, their mood swings more strongly.

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2. Latitude / Sunlight / Climate

This is the most powerful external factor.

• People living in countries with winters and short days have higher rates of SAD.

• Among bipolar populations, seasonal patterns are significantly more frequent.

• Even in tropical countries, seasonal patterns are observed, such as:
• Depression during prolonged rainy seasons with little sunlight
• Elevation during hot seasons with intense sunlight

Reason:

• Sunlight directly regulates the SCN.
• Rapid changes in light → circadian system destabilizes quickly.
• In bipolar disorder, where this system is already fragile → destabilization is more severe.

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3. Chronotype — Night Owl vs Morning Lark

Evening-type (sleeping late–waking late) individuals are at the highest risk for seasonal dysregulation because:

• It is harder for them to reset sleep schedules.
• They miss morning sunlight.
• Their internal clock is continually delayed.
• The SCN finds it harder to synchronize.
• Dopamine peaks at night → mania can emerge more easily.
• In seasons with less light → they may feel sleepy all day.

Recent research shows chronotype is associated with:

• ADHD
• Impulsivity
• Circadian misalignment

→ All of which accelerate bipolar mood swings.

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4. Lifestyle / Sleep Hygiene

This factor can “flip the switch” of the disorder directly.

Concrete lifestyle triggers include:

• Working night shifts
• Staying up late every day
• Using bright lights/screens at night
• Frequent travel across time zones (jet lag)
• Frequently changing work start times
• Nightlife with sleeping at dawn
• Sleep deprivation for work or gaming

These behaviors damage the circadian rhythm → triggering hypomania or seasonal depressive relapse easily, especially in sensitive seasons (winter/summer).

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5. Gender and Hormones

Across cohorts in many countries, studies show:

• Women have higher rates of:
• Rapid cycling
• Seasonal depression
• Atypical symptoms
• Seasonal binge eating

than men.

Biological reasons:

• Fluctuations in estrogen/progesterone affect serotonin and circadian rhythms.
• In some periods, women are less responsive to light than men.
• Sleep–mood coupling is stronger and more reactive in women than in men.

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6. Psychosocial Triggers

Even though seasonal patterns are biologically based, stress “ignites the episode” faster, such as:

• End-of-year stress
• Financial problems
• Heavy workloads at quarter-end
• Family issues during New Year/holiday periods
• Loneliness during winter (holiday blues)
• Extreme heat making it difficult to sleep in summer

Mechanism:
Stress → increased cortisol → SCN dysregulation → sleep disruption → mood destabilization → episode onset.

Especially in “bipolar patients with fragile brain clocks,” sensitivity is multiplied.

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7. Past Seasonal Response History

Sometimes it’s not the illness alone, but the person’s life pattern, for example:

• Severe depressive episodes in rainy seasons during adolescence
• Elevated mood during summer school terms
• Chronic sleep disruption every winter

The brain encodes:

“This season = this mood pattern.”

It is like a seasonal template set in childhood and carried through life.

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8. Medication Use / Discontinuation

Some individuals have seasonal relapses because:

• They stop mood stabilizers in seasons when they feel “better.”
• They increase caffeine/energy drink intake in winter.
• They use antidepressants alone in winter depression → then switch up into hypomania when the season changes.
• They overuse hypnotics in winter.

All of this ties back to circadian regulation and becomes a risk factor that clinicians need to carefully monitor.

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9. Immunity and Seasonal Inflammation

Immunopsychiatry research finds that:

• Winter = inflammatory cytokines increase.
• Summer = some cytokines decrease.
• Inflammation triggers depressive symptoms.
• When inflammation drops → arousal increases → hypomania can replace depression.

This explains why some individuals “swing between depression and elevation” according to seasons, like a biological rhythm.

🩺 Treatment & Management — Approaches to Treatment and Management

KEY: Treatment must balance between:

• Controlling bipolar disorder (manic prevention), and
• Managing seasonal depression / circadian dysregulation.

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1. Mood Stabilizers as the Core

Lithium, Valproate, Lamotrigine, Carbamazepine, etc., as per standard bipolar treatment.

Key focus in patients with a seasonal pattern:

• Planning to adjust doses in advance before entering high-risk seasons (some clinics use maintenance strategies that adjust according to season).
• Carefully monitoring for rapid cycling when increasing or decreasing medication.

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2. Atypical Antipsychotics

Quetiapine, Olanzapine, Lurasidone, etc., are used both to:

• Treat manic / hypomanic episodes.
• Treat bipolar depression in specific regimens.

There is evidence supporting these drugs in bipolar depression more than antidepressant monotherapy, in order to reduce the risk of switching into mania.

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3. Antidepressants — Use with Great Caution

In individuals with bipolar + seasonal depression, using SSRIs/SNRIs/Bupropion, etc.:

• May help winter depression.
• But carry a risk of triggering mania / rapid cycling.

Common practice:

• If necessary, they are usually used together with a mood stabilizer.

• Some cases use them as “seasonal prophylaxis,” for example:
• Start 1–2 months before the depressive season, and
• Discontinue after the season ends, under close monitoring by the clinician. Wikipedia+1

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4. Light Therapy (Phototherapy) — Effective but Mania Risk

Light therapy is first-line in SAD and subsyndromal SAD.

In bipolar patients with a seasonal pattern:

• Light therapy can be very helpful for winter depression.
• But there are reports that it can trigger (hypo)mania in some patients → It must therefore be used cautiously, in combination with mood stabilizers and close monitoring. Wikipedia+1

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5. Psychotherapy

• CBT-SAD (CBT adapted for SAD)
• Focuses on modifying thoughts and behaviors related to seasons, light, and daily routines.

• Interpersonal and Social Rhythm Therapy (IPSRT)
• Directly targets circadian regulation: emphasizes stabilizing the timing of sleep, wake, meals, and work as “time anchors.”
• Highly suitable for bipolar patients whose mood is very sensitive to changes in routine. PubMed Central+1

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6. Lifestyle & Self-Management

• Keep a consistent sleep–wake schedule, even on weekends.
• Get morning sunlight regularly when possible (or use a light box under medical guidance).
• Exercise regularly, especially outdoors in the morning or early afternoon.
• Reduce intense blue light exposure before bed; optimize the sleep environment.
• Plan life around high-risk seasons, e.g., avoid taking on extremely stressful work during seasons when depression usually hits.
• Use mood charts/apps to track mood, sleep, and light exposure, to detect patterns and design preventive strategies. BioMed Central+2 Nature+2

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7. Monitoring & Prevention Strategy

• Schedule more frequent follow-up visits “before entering high-risk seasons.”

• Involve family/partners in recognizing early warning signs such as:
• Sleeping less but not feeling tired
• Talking faster / taking on too many projects
• Or conversely, sleeping much more, becoming unusually inactive, avoiding social contact

• Develop a crisis plan in advance, e.g.:
• If symptoms reach a certain level → who to call → how to adjust medications (according to the clinician’s plan).

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📝 Notes — Key Observations

• Not everyone who “doesn’t like winter” has the seasonal specifier.
  There must be depressive or manic episodes that reach full diagnostic threshold, recurring with a clear pattern over many years.

• Distinguish from “winter blues / subsyndromal SAD / s-SAD.”
• Those groups have milder symptoms and do not meet full episode criteria. Wikipedia+1

• Many bipolar patients were diagnosed as having “SAD” or “MDD with seasonal pattern” for years, until one day a clear hypomanic episode appeared, revealing that they actually had Bipolar II with a seasonal pattern.

• Adding the specifier “with seasonal pattern” helps clinicians plan ahead, for example:
• Adjusting medications,
• Preparing light therapy,
• Structuring life before entering a risky season.

• Current research suggests that seasonality functions as a “modifier” of bipolar disorder—it changes episode frequency, severity, and comorbidities, but does not create a completely different disease. PubMed Central+2 PubMed+2

• All of this material is academic/general information.
  In real life, anyone who suspects they might fit this pattern should be assessed by a psychiatrist or clinical psychologist. Self-diagnosis is not recommended.

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📚 References — Sources

📘 Textbooks / Diagnostic Manuals
American Psychiatric Association. (2022). Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR). (Bipolar and Related Disorders + Specifier: With Seasonal Pattern)

World Health Organization. (2022). ICD-11: International Classification of Diseases 11th Revision. (Code 6A80.4 — Seasonal pattern of mood episode onset)

📗 Research / Chronobiology & Bipolar
Geoffroy, P. A. et al. (2013). Bipolar disorder with seasonal pattern: Clinical characteristics and gender influences. Chronobiology International, 30(9).

Fico, G. et al. (2021). Clinical correlates of seasonality in bipolar disorder. Journal of Affective Disorders.

Geoffroy, P. A., Kupfer, D., & Etain, B. (2014). Seasonality and bipolar disorder: A systematic review. Journal of Affective Disorders, 168.

Wirz-Justice, A. (2018). Circadian rhythms and mood disorders: Time to see the light. European Neuropsychopharmacology.

McClung, C. A. (2013). How might circadian rhythms control mood? Let me count the ways… Biological Psychiatry.

📕 Clock Genes / Neurobiology
Etain, B. et al. (2014). A review of circadian genes as potential risk factors in bipolar disorders. Journal of Affective Disorders.

Lamont, E. W. et al. (2010). Clock genes and bipolar disorder: Links and hypotheses. Chronobiology International.

Bunney, B. G. et al. (2015). Circadian dysregulation in mood disorders. Molecular Psychiatry.

📙 Seasonal Affective Disorder & Light Biology
Rosenthal, N. E. et al. (1984). Seasonal Affective Disorder: A description of the syndrome and preliminary findings with light therapy. Archives of General Psychiatry (the classic SAD paper).

Lewy, A. J. (2009). Light treatment and circadian rhythms in mood disorders. Dialogues in Clinical Neuroscience.

Roecklein, K. A. & Rohan, K. J. (2005). Seasonal Affective Disorder: An overview and update. Psychiatric Clinics of North America.

📒 Sleep–Mood Interaction / IPSRT
Frank, E. et al. (2005). Two-year outcomes for interpersonal and social rhythm therapy in bipolar I disorder. Archives of General Psychiatry.

Harvey, A. G. (2008). Sleep and circadian functioning in bipolar disorder. Current Opinion in Psychiatry.

📔 Immunology / Seasonal Gene Expression
Dopico, X. C. et al. (2015). Widespread seasonal gene expression reveals annual differences in human immunity. Nature Communications.

Zimmerman, M. et al. (2022). Inflammation and seasonality in mood disorders. Current Psychiatry Reports.

📓 Tools / Assessment
Rosenthal, N. E. (1987). Seasonal Pattern Assessment Questionnaire (SPAQ): Validation and clinical utility.

Youngstrom, E. A. (2013). Charting mood cycles: The clinical value of mood charts and life charts in bipolar disorder.

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