Comparison of objective and subjective assessments of sleep time in subjects with bipolar disorder

Sleep disturbance is a core feature of bipolar disorder. To date there are a limited number of studies that compare subjective and objective measures of sleep in populations of subjects with mood disorders. This study evaluated the relationship between subjective and objective measurements of total sleep time (TST) in a bipolar type I disorder (BD I) population.

Thirty-nine subjects diagnosed with BD I participated in the study. Mood symptoms were assessed via YMRS and IDS-30-C. Subjects wore an actigraph device and maintained a sleep diary for seven consecutive days. Differences between TST as estimated via sleep diaries and actigraphy were calculated.

Objective and subjective measures of TST were significantly correlated (r=0.5151, p=0.0008). Secondary analysis revealed that the severity of depressive symptoms did correlate to this discrepancy (t=2.65, p=0.01).

The impact that medications have on the accuracy of TST reported was not investigated. Also, sleep diaries may have acted to prompt subjects to pay closer attention to their sleep habits and therefore more accurately report TST than in the average clinical setting.

The results of the current study demonstrate a significant correlation between the estimation of TST as measured objectively via actigraphy and subjectively via sleep diaries in BD patients. Mood symptomotology might impact the accuracy of TST reported. Further study is warranted.