Currently, no evidence connects sundown syndrome and bipolar disorder. However, evidence does suggest a link between dementia and bipolar disorder.

Sundown syndrome is a set of symptoms that occur between the late afternoon and the evening hours. Symptoms may include restlessness, irritability, anxiety, and behavioral symptoms.

Scientific literature often links sundown syndrome to dementia, though some report the syndrome occurring in older adults not living with dementia.

Current evidence does not suggest a link between bipolar disorder and sundown syndrome. However, it does suggest bipolar disorder may increase the risk of dementia. People with bipolar disorder may also experience sleep disturbances and worsening symptoms at night.

This article reviews whether sundown syndrome can occur with bipolar disorder. It also discusses symptoms of sundown syndrome, possible causes of evening symptoms in bipolar disorder, tips for coping with bipolar symptoms, and more.

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Evidence does not suggest a link between sundown syndrome and bipolar disorder. However, a link between bipolar disorder and dementia may exist.

Affected populations

Most cases of sundown syndrome occur in people living with dementia, such as those with Alzheimer’s disease. It can also occur in different populations of older people, though less frequently.

A 2017 study noted the syndrome can occur in people who experience institutionalization, such as those living in a hospital or assisted living home. Beyond dementia, the study does not detail the mental and physical conditions for which a person may receive assisted living care.

Bipolar disorder and dementia

In a 2017 review, researchers noted that a history of bipolar disorder greatly increases the chances that an older adult will develop dementia. The exact mechanism of connection between the conditions requires further studies.

A 2020 study found evidence suggesting that bipolar disorder may relate to a type of dementia called behavioral variant frontotemporal dementia. The authors suggest the two conditions share similar underlying causes and symptoms.

To date, no studies have looked at the number of people with bipolar disorder who develop dementia and sundown syndrome.

Read about bipolar disorder.

Sundown syndrome is not a medical condition. Instead, it is a set of symptoms that often occur in the late afternoon and early evening, typically around 4–6 p.m.

The syndrome is similar to delirium, which occurs when there are changes in consciousness and orientation. It also causes mental confusion.

Common symptoms can include behavioral and psychological changes, such as:

A person may not experience all of these symptoms.

Symptoms also do not typically occur at a set time each day. However, people often experience them in the late afternoon and early evening.

Research does not currently connect bipolar disorder and sundown syndrome. However, since bipolar disorder affects people differently, some people may notice their symptoms worsen or change during the evening hours.

In some cases, these symptoms may resemble those of sundown syndrome.

Evening chronotype

Research suggests that people living with bipolar disorder often display what is called an evening chronotype. “Chronotype” describes the time of day when a person feels more awake or alert. Common types include morning and evening.

Evening wakefulness may contribute to sleep issues and may account for heightened bipolar symptoms in the evening hours.

Body clock dysfunction

Body clock dysfunction refers to changes in how a person’s circadian rhythm operates. The circadian rhythm is the internal process that controls when a person feels alert or tired.

The circadian rhythm responds to changes in light and dark. The presence of light helps a person wake up in the morning, while its absence helps a person fall asleep in the evening. When a person does not respond to light changes, it can lead to sleep disruption.

According to a 2018 review, many studies suggest circadian rhythm disorder is a characteristic of bipolar disorder.

Bipolar disorder subtype

Differences among people and types of bipolar disorder may result in a person experiencing more symptoms in the evening compared with the daytime hours.

Four types of bipolar disorder exist, including:

  • Bipolar I: This type features longer-lasting manic episodes and may include depressive symptoms
  • Bipolar II: Manic episodes with this type tend to be less severe compared with bipolar I disorder. Hypomanic episodes are similar to manic episodes but not as intense.
  • Cyclothymic disorder: This type involves symptoms of mania and depression that do not fill the full criteria of bipolar disorder.
  • Other types: This includes types that do not fit into any of the other categories.

Symptom onset can vary between people and types of bipolar disorder. For example, a 2019 study found that people living with bipolar I disorder experience worse mood instability compared with those who have bipolar II.

Read more about the types of bipolar disorder.

Medication side effects

No studies link medication side effects to evening symptoms. However, a person can experience side effects from medications they take to treat bipolar disorder. The side effects may present similarly to symptoms of sundown syndrome.

For example, evidence suggests that taking lithium for bipolar disorder can cause issues with mental acuity, concentration, and memory. These side effects resemble some symptoms people experience as part of sundown syndrome.

Read more about medications for bipolar disorder.

People living with bipolar disorder can try the following steps to help manage symptoms that tend to occur late in the afternoon or evening:

Keep a consistent schedule

A consistent sleep schedule may help with insomnia or other sleep disturbances. A person can try to do the following as much as possible:

  • wake up at the same time each day
  • go to sleep at the same time each night
  • exercise and eat meals at consistent times
  • engage in relaxing activities in the evening

Get regular exercise

Regular exercise may help with getting regular sleep. Exercise can:

  • reduce stress levels
  • promote good quality sleep
  • improve overall quality of life
  • reduce depression or anxiety symptoms

The Centers for Disease Control and Prevention (CDC) recommends people get about 150 minutes of activity a week. People can break this down into five 30-minute workouts.

Start a wind-down routine

A wind-down routine involves any activity that helps a person relax.

Examples may include:

  • reading
  • painting
  • meditation
  • doing puzzles
  • watching television
  • listening to soft music
  • taking a warm bath or shower
  • doing yoga or other stretching-based exercises

Learn more about relaxation techniques.

Follow the natural patterns of light and dark

Following natural patterns of light and dark may help reset a person’s circadian rhythm. To take advantage of the light and dark cycles, a person may find the following helpful:

  • opening all shutters and curtains in the morning
  • going outside for a few minutes after waking up
  • turning lights on during overcast, rainy days
  • dimming lights at night

Light therapy may also help, particularly during winter months.

A person may wish to speak with a healthcare or mental health professional if they notice bipolar symptoms worsening at night. They may need to try different therapies or medications to help suppress or manage symptoms in the evening.

People living with bipolar disorder often experience sleep disturbances. A healthcare professional may recommend specific therapies to help a person get to sleep and stay asleep.

Bipolar disorder resources

Visit our dedicated hub for more research-backed information and in-depth resources on bipolar disorder.

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The following sections provide answers to common questions about bipolar disorder.

What is the biggest trigger for bipolar disorder?

In a 2023 review of over 100 studies, the most common triggers for mania in bipolar disorder included:

Limited data suggests that triggers for depressive episodes include:

  • stress
  • decreased sleep
  • fasting

Why is bipolar disorder worse at night?

Experts do not know the exact reason for bipolar disorder symptoms worsening at night for some people. However, many consider sleep disturbances a defining characteristic of bipolar disorder.

There is no evidence that bipolar disorder connects directly to sundown syndrome. However, a person may experience sleep disturbances or worsening bipolar symptoms in the evening that may resemble the symptoms of sundown syndrome.

Additionally, bipolar disorder may increase the risk of developing dementia, a condition researchers often associate with sundown syndrome.

People can try taking steps to help manage sleep issues and other bipolar symptoms in the evening. This may involve making changes to routines, such as setting a usual bedtime and waking time, partaking in regular exercise, and creating time for relaxation.