Seasonal changes in factors such as sunlight and temperature can impact symptoms of bipolar disorder.

You may experience seasonal changes in the symptoms of bipolar disorder. Mania and depression can each be impacted differently by seasonal changes.

Knowing how the seasons and other environmental factors affect bipolar symptoms can help you better manage your condition.

Your circadian rhythm is powered by the suprachiasmatic nucleus in the brain. This part of the brain regulates physiological circadian rhythms by detecting levels of sunlight and processing other environmental factors.

Individuals with bipolar disorder have altered circadian and seasonal rhythms and sometimes demonstrate seasonal patterns of depressive and manic episodes. In a 2021 review of 51 studies, researchers found a few patterns:

  • Hospital admissions for bipolar depressive episodes peak in early winter.
  • Hospitalizations for manic episodes are more common in spring and summer.
  • Seasonal variations were more common in women with bipolar disorder.

A 2021 analysis of 4,876 people with bipolar I disorder from 71 different geographic locations found that higher rates of suicide attempts were present in locations farther from the equator. These locations have more solar variation, meaning that the amount of radiation given off by the sun shifts drastically throughout the year.

Help is available

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

  • Call or text the 988 Suicide and Crisis Lifeline at 988 or chat at 988lifeline.org. Caring counselors are available to listen and provide free and confidential support 24/7.
  • Text HOME to the Crisis Text Line at 741741 to connect with a volunteer crisis counselor for free and confidential support 24/7.
  • Not in the United States? Find a helpline in your country with Befrienders Worldwide.
  • Call 911 or your local emergency services number if you feel safe to do so.

Other meteorological factors

In addition to sunlight, a 2020 study found that other meteorological factors can have an effect on bipolar disorder, including:

  • minimum and maximum temperatures
  • rainfall
  • cloudiness
  • atmospheric pressure

A 2019 study found that more people with bipolar disorder were admitted to the emergency psychiatric ward on days with higher temperatures and higher solar radiation.

Winter-pattern SAD causes some people to experience depression during the colder, darker months. SAD is more common in individuals with bipolar disorder, specifically bipolar II disorder.

Some causes of SAD include:

  • reduced serotonin
  • too little sunlight
  • altered melatonin levels

A 2018 study found that photoperiod — the period of time each day when a person is exposed to light — is a key element in bipolar disorder.

The researchers found that people with bipolar disorder were hospitalized for depression in winter, when exposure to light is reduced due to shorter days.

Treating SAD

If you have SAD, treatment can include:

Talk with your doctor about which treatment is best for you.

Lifestyle habits, like getting regular exercise and sun exposure, may also help minimize SAD symptoms.

On the other hand, summer-pattern SAD can affect the moods of people with bipolar disorder during the sunnier, warmer months.

The same 2018 study found that more people were hospitalized for mania in spring and summer when daylight exposure is highest throughout the year.

Light therapy is recommended by the International Society of Bipolar Disorders as a treatment for acute bipolar depression, but clinical trials on the therapy are limited.

In one trial, 58 patients were given light therapy for 7 to 21 days, and 55% experienced remission of depressive symptoms by the end of treatment. Patients received light treatment using a lamp for 30 minutes during morning hours, the time when bright light is believed to have the best effect on depression.

However, two patients in the study experienced hypomanic episodes while undergoing light therapy.

A 2020 review of studies found that light therapy had a significant antidepressant effect in individuals with bipolar disorder. However, the researchers noted that none of the studies involved investigated the effects of light therapy on manic symptoms or the recurrence of mood episodes.

More robust research is needed to verify the effect of light therapy on bipolar disorder.

Talk with your doctor about whether light therapy could help with seasonal depression. It’s important to understand the risk of triggering a manic episode.

Managing seasonal mania

Less research has been done on treating summer-pattern SAD, but understanding how the change of seasons may impact the disorder is a start.

Individuals with summer-pattern SAD may have reduced melatonin levels, which can cause you to experience:

However, keep in mind that these symptoms have not been researched.

Healthy sleep habits, consistency with prescribed medications and other treatments, and stress reduction strategies can help prevent manic episodes during the hot summer months.

Bipolar disorder symptoms can follow a seasonal pattern. You may experience more depressive moods in the winter or darker months and be at higher risk for mania in the summer and spring.

Being aware of changes in your circadian rhythm and seasonal symptoms can help you and your healthcare professional manage bipolar depression.