Is bipolar disorder worse in the fall?

Seasonal Patterns in Bipolar Disorder

Yes, bipolar disorder demonstrates clear seasonal worsening, with depressive episodes peaking in fall/early winter and manic episodes peaking in spring/summer, affecting approximately 25% of depressive episodes and 15% of manic episodes. 1

Evidence for Fall/Winter Worsening

Depressive episodes in bipolar disorder show a distinct peak in early winter, with a secondary peak in summer. 1 This seasonal pattern is widely replicated across multiple studies worldwide and represents one of the most consistent findings in bipolar disorder research.

Clinical Characteristics of Seasonal Pattern

• Approximately 25% of depressive episodes in bipolar disorder follow a seasonal pattern, which is higher than the 15% rate seen with manic episodes 1
• Patients with seasonal pattern depression have a more complex and severe clinical profile, including:
  • Higher rates of bipolar II subtype 1
  • More frequent comorbid eating disorders 1
  • Increased number of total relapses 1
  • Greater likelihood of rapid cycling 1

Gender-Specific Patterns

• Women with bipolar disorder demonstrate a bimodal seasonal distribution with peak hospitalizations in both spring and fall 2
• Men show a single peak admission rate in springtime 2
• This suggests women may be particularly vulnerable to fall worsening of symptoms

Underlying Mechanisms

The fall/winter worsening appears driven by several interconnected pathways:

• Decreased solar insolation during fall triggers changes in the suprachiasmatic nucleus, which regulates circadian rhythms that are already disrupted in bipolar patients 3, 4
• The rate of change in sunlight intensity (not just absolute levels) during seasonal transitions may be particularly destabilizing 3
• Two key pathways mediate seasonal effects:
  • Light-to-cortex serotonin transporter pathway 4
  • Light-to-melatonin synthesis pathway 4

Clinical Implications

Clinicians should anticipate increased risk of depressive episodes during fall and early winter months, particularly in patients with prior seasonal patterns. 1 This requires:

• Proactive monitoring starting in late summer/early fall
• Consideration of preventive medication adjustments before symptom emergence
• Assessment for seasonal pattern history, as this predicts more severe disease course 1
• Recognition that seasonal patterns occur even in patients maintained on mood stabilizers 4

Common Pitfall

Do not assume seasonal worsening only affects patients with formal "seasonal affective disorder" diagnosis—seasonal fluctuations in mood and behavior are more pronounced in all individuals with bipolar disorder compared to those with unipolar depression or healthy controls 1, making this a core feature of the illness rather than a distinct subtype.