Sleep in remitted bipolar disorder: a naturalistic case-control study using actigraphy

Area of Science:

• Neuroscience
• Psychiatry
• Sleep Medicine

Background:

• Previous actigraphy studies suggest sleep and circadian rhythm disruptions in bipolar disorder (BD).
• Methodological limitations and unaddressed confounders have previously undermined these findings.
• This study aims to provide a more robust analysis by controlling for key variables.

Purpose of the Study:

• To compare subjective and objective sleep measures between euthymic bipolar disorder patients and healthy controls.
• To identify specific sleep parameters that can differentiate between these two groups.
• To assess the diagnostic utility of sleep measures in bipolar disorder.

Main Methods:

• Compared 26 euthymic BD cases and 29 healthy controls (HC) using the Pittsburgh Sleep Questionnaire Inventory (PSQI) and actigraphy over 21 days.
• Utilized multivariate generalized linear modeling (GLM) to analyze differences in sleep measures.
• Employed backward stepwise linear regression (BSLR) to identify key differentiating variables and classification accuracy.

Main Results:

• Significant differences were found between BD cases and HC in five PSQI items, four actigraphy mean scores, and five actigraphy variability measures.
• A combination of four variables (mean sleep duration, mean sleep latency, variability of fragmentation index, and PSQI daytime dysfunction score) correctly classified 89% of participants.
• These results indicate distinct sleep profiles in euthymic BD patients.

Conclusions:

• Adequately controlling for confounders like age, gender, daytime sleepiness, mood symptoms, BMI, and sleep apnea risk is crucial.
• Quantitative (mean scores) and qualitative (variability) sleep features can effectively differentiate euthymic BD cases from HC.
• These findings support the utility of detailed sleep assessments in the context of bipolar disorder.