Sleep Irregularities in Bipolar Disorder

Phases of Bipolar Disorder
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Bipolar Disorder (BD) Background

Bipolar Disorder (BD) affects 2% of the world population, giving rise to a suicide rate of 20 times that of the general population. BD is a mood disorder in which individuals experience episodes of mania, hypomania, hyperthymia, depression, and mixed episodes[1]. A symptom that is found to recur after manic or depressive episodes is sleep disturbance. Particularly, during the inter-episode period, where no symptomologies are present, irregularities in sleep patterns are evident[2]. Individuals are reported to have longer sleep times, less efficient sleep, and more variation in sleep with constant periods of wakening[2]. A recent study reported that the sleep of individuals diagnosed with BD is similar to that of insomniacs. Insomniacs tend to overestimate the amount of time it takes them to fall asleep, as well as underestimate their total sleep time, which is a characteristic similar to what individuals with BD would report[3].

Bipolar Disorder
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Characteristics of Bipolar Disorder Sleep

A study by Millar (2004) was the first to compare remitted bipolar patients with controls in a naturalistic setting. Hyperactivity is a feature of mania and reduced activity is characteristic of depression; reduced sleep and increased activity are related to the onset of mania. Sleep abnormalities may also lead to mood disorders, which are common even when not in an episode. All participants in this study were of Bipolar I Disorder type and ranged in age from 26-68 years. Bipolar Disorder group rated themselves as more depressed than control group and they slept longer, as well as took longer to fall asleep, and had less efficient sleep than controls[4]. The study also found that there was more variability in night-time waking with periods of cycling wake and sleep due to circadian rhythm disruptions. Individuals with Bipolar Disorder also report less stable sleep histories. Changes in sleep cylces may also be predictive of relapse in BD.
Another study examined the sleep of BD patients over 5 consecutive nights and found the sleep of ten remitted patients to have a higher percentage of stage 1 sleep and more disturbed sleep than controls[5]. Guide to Sleep Problems See: Sleep deprivation

Depression and Mania
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Sleep Disturbances

During Euthymic Phase

Euthymic (absence of any symptomologies) BD I and II participants were studied where reports of mild sleep disturbance before the study were evident[2]. Sleep disturbance impacts the quality of life in such domains as social and environmental. It was found that sleep disturbance was not related to age, gender, cycling in previous year, or the type of BD they had and sleep disturbance was less common in individuals with a history of psychosis. It was also reported that sleep disturbances were more common in those with a history of suicide attempts and hypomanic symptoms. Inducing sleep deprivation also causes mania or hypomania in individuals with BD, but can have an antidepressant effect in depressed BD patients. When look at the effect of medications, there was a statistically significant correlation between sleep disturbance and use of anticonvulsants. An example of this is gabapentin, which is commonly used for insomnia. Lastly, the study reported that sleep disturbance was correlated with a greater risk for recurrent mood episodes.

Comparison to Insomnia

Sleep disturbance was a common predictor of mania and the sixth most common predictor of depression; both of which are typical of BD[3]. This study looked at sleep patterns in euthymic patients in the absence of BD symptomology, where they had a clinically significant sleep problem. 55% met diagnostic criteria for insomnia. The sleep of BD patients was similar to insomniacs. BD patients and insomnia group both overestimated the time it takes to fall asleep, and underestimated how much total sleep they got. These misperceptions of sleep also have a cognitive variable; individuals are now aware of and thinking about their supposed inadequate sleep and as a result, anxiety develops[3]. The study reports that BD patients have a genetic predisposition for circadian rhythm instability.

Therapies for BD patients with sleep problems, which are also used for insomniacs:
1) Stimulus control —>altering the negative conditioning between the bedroom and lack of sleep
2) Sleep hygiene —>educating individuals to understand the behaviours that disrupt sleep
3) Cognitive therapy —>changing their negative beliefs about sleep

Disturbances in psychological functioning cause a disruption of routine sleep and therefore, circadian-regulated sleep cycles, which subsequently causes an episode.HHMI-How Biological Clocks Work

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Comorbidities with Medical Issues

Individuals with BD commonly have comorbid medical disorders. Treating the negative effects of these disorders will lead to a reduction in adverse outcomes for these individuals
A study showed that there are a staggeringly high amount of medical comorbidities with Bipolar Disorder[6]. It was found that higher rates of substance use disorders, sexually transmitted infections (eg. HIV) were common among Bipolar patients. Antipsychotics and mood stabilizers increased the risk of metabolic diseases such as diabetes and cardiovascular disease. Most common among individuals with Bipolar Disorder are cardiovascular comorbidities such as hypertension. This affected 1/3 of individuals with BD. Endocrine comorbidities (diabetes), alcohol use disorder, cocaine use disorder and lower back pain[6]. Tailoring treatments to each individual with BD is necessary.

Sleep Apnea

It has been found that there are correlations of sleep apnea with mood disorders, including depression and BD. Atypical antipsychotics used by individuals with BD cause a side effect of increasing central adipose tissue, which increases the risk for sleep apnea, specifically obstructive sleep apnea[7].

Stages of Sleep
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REM Sleep Disturbances

A study conducted by Eidelman (2010) aimed to assess the association between the euthymic phase of BD and sleep architecture. Euthymic individuals show patterns of sleep characterized by increased REM activity[8]. Slow wave sleep (SWS) sleep in stages 3 and 4 is thought to be involved in memory consolidation and cell regeneration, which serve as restorative functions in healthy individuals. SWS activity was decreased in BD and in unipolar depression. It was noted that in the BD group, there was greater REM density. It was suggested that there was a disturbance in sleep of individuals with BD because of this increased density of REM sleep. A longer duration of the first REM onset period was correlated with more manic symptoms, while greater REM density associated with depressive symptoms[8]. The study also found that a higher percentage of stage 2 sleep was correlated with lower levels of manic symptoms, which is consistent with hypothesis that stage 2 provides a restorative function for individuals. Treatment seems to be increased in effectiveness with increased stage 2 sleep in individuals with BD. See: Sleep homeostasis See also: Narcolepsy

Cognitive Dysfunction

It has been shown that there are significant cognitive dysfunctions seen in patients with BD[9]. Participants were those with BD and were given a cognitive assessment test. They were compared to individuals w/ mild cognitive impairments (MCI) and healthy controls. Individuals with MCI showed a reduction in cognition subjectively and objectively without any functional impairments. Individuals were determined to have BD by being fully euthymic for at least 1 month prior to inclusion in study. The control group outperformed the BD and MCI group, but the BD and MCI group performed similarly. The overall cognitive function of euthymic BD patients was similar to MCI on some domains, even though indivuals with BD were on average 30 years younger[9]. It was found that within BD, females performed worse than males. It was shown that neurocognitive function was not dependant on the medications being taken. Results indicated that BD and MCI groups had equivalent functioning in memory, executive function, verbal function, and information processing speed. The MCI group outperformed BD group in domains of attention, motor skills and visual-spatial processing.

Another study by Robinson (2006) reported that many patients do not regain premorbid levels of cognitive functioning after their affective symptoms reside[10]. The severity of cognitive dysfunction is related to the number of BD episodes, number of hospital admissions and the duration of illness. Manic episodes seem to be related to delayed verbal memory as well as some aspects of executive function, while depression is related to a broader amount of impairments[10]. Those individuals at genetically high risk for BD displayed deficits in response inhibition, planning, and mental manipulation as well as verbal memory.

The Importance of Good Sleep
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Bibliography
1. Smith, D.J., Whitham, E.A., Ghaemi, S.N. Bipolar Disoder. Handbook of Clinical Neurology (2012)106:251-63.
2. Sylvia, L.G. et al. Sleep disturbance in euthymic bipolar patients. Journal of Psychopharmacology (2012)26(8):1108-12.
3. Harvey, A.G. et al. Sleep-related functioning in euthymic patients with bipolar disorder, patients with insomnia, and subjects without sleep problems. Am J Psychiatry (2005)162:50-57.
4. Millar, A., Espie, C.A., Scott, J. The sleep of remitted bipolar outpatients: a controlled naturalistic study using actigraphy. Journal of Affective Disorders (2004)80:145-53.
5. Knowles, J.B. The sleep of remitted bipolar depressives: comparison with sex- and age-matched controls. Canadian Journal of Psychiatry (1986)31:295-98.
6. Kilbourne, A.M. et al. Burden of general medical conditions among individuals with bipolar disorder. Bipolar Disorders (2004)6:368-73.
7. Baran, A.S., Richert, A.C. Obstructive sleep apnea and depression. CNS Spectrums (2003)8:128-34.
8. Eidelman, P. et al. Sleep architecture as correlate and predictor of symptoms and impairment in inter-episode bipolar disorder: taking on the challenge of medication effects. J. Sleep Res. (2010)19:516-24.
9. Osher, Y. et al. Computerized testing of neurocognitive function in euthymic bipolar patients compared to those with mild cognitive impairment and cognitively healthy controls. Psychotherapy and Psychosomatics (2011)80:298-303.
10. Robinson, L.J., Ferrier, I.N. Evolution of cognitive impairment in bipolar disorder: a systematic review of cross-sectional evidence. Bipolar Disorders (2006)8:103-116.

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