Subjective sleep assessment reliable in bipolar disorder
medwireNews: Total sleep time (TST) can be accurately monitored in bipolar disorder patients using sleep diaries, suggest findings from a naturalistic study.
But the results, published in the Journal of Affective Disorders, also showed that mood symptoms may affect the accuracy.
“The degree of manic symptoms had little impact on the accuracy of TST reported while subjects experiencing greater degrees of depression tended to underestimate TST,” report the study researchers R Gonzalez (University of Texas Health Science Center San Antonio, USA) and colleagues.
Sleep diaries completed by 39 patients with bipolar I disorder over a 1-week period showed an average subjective TST of 447.33 minutes per night. This correlated significantly with an average TST of 406.53 minutes recorded using actigraphy.
This supports “the notion that, by using sleep diaries, symptomatic bipolar patients are able to accurately report TST,” say the researchers, who add that “subjects tended to describe their sleep duration with considerable accuracy when compared to the objective measurements of TST.”
However, increased severity of depressive symptoms contributed significantly to a greater discrepancy between objective and subjective assessments of TST.
The researchers suggest that variability in TST may be associated with variations in sleep architecture, and that it would be worth testing correlations between subjective and objective measures of other types of sleep disturbances, such as number of awakenings and sleep fragmentation.
Indeed, they note that the standard deviations were “rather large” for both subjective and objective accounts of sleep estimation in their study, which suggests that variability in TST in bipolar disorder patients could be “a clinical signature of the disorder.”
Given the prominence of sleep disturbance in patients with bipolar disorder, Gonzalez et al say that understanding the capability of bipolar disorder patients to accurately record and report sleep quantity has “considerable clinical benefit.”
Further examination of the reliability of subjective assessment of sleep factors among bipolar disorder patients is therefore warranted, they conclude.
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Lucy Piper, Senior medwireNews Reporter