Sleep disturbance

What is sleep disturbance?

People with a mental illness may show disturbances in the amount or quality of sleep they receive. Typically sleep follows a characteristic pattern of four stages, where stage 1 is a state of drowsiness and early sleep; stage 2 comprises the largest component of the sleep cycle and is the first complete loss of awareness of the external environment; stage 3 is a deep, slow-wave sleep; and the fourth stage is rapid eye movement (REM) sleep where memorable dreaming and muscle paralysis occurs.

Sleep disturbance can be measured in many ways, including the total sleep time, the sleep latency (the length of time it takes from full wakefulness to sleep), and the sleep efficiency index (the amount of time spent asleep while in bed). Sleep latency can have varying definitions, particularly regarding the definition of “asleep” – some studies define this more strictly as the time from lights out until 10 consecutive minutes of stages 2, 3 or 4, while other studies define the latency more leniently as the time from lights out until the first signs of stage 2 sleep.

What is the evidence for sleep disturbance?

Moderate to high quality evidence suggests around 30% of people with bipolar disorder have hypersomnia. There were large effects of more time in bed and poorer sleep quality; medium-sized effects of less sleep efficacy, more sleep time (particularly stage 1), and more awakenings; and small effects of more sleep latency and wakefulness.

Sleep disturbances may be apparent prior to the onset of bipolar disorder, including during childhood and adolescence. A decreased need for sleep may precede a manic episode, while hypersomnia may precede a depressive episode. Insomnia can precede either a manic or a depressive episode

Moderate quality evidence finds a medium-sized effect of lower relative amplitude of the sleep-wake cycle in people with bipolar disorder than people at familial or clinical risk of bipolar disorder.

June 2020

Last updated at: 12:32 am, 29th June 2020
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