Associations between daily affect and sleep vary by sleep assessment type: What can ambulatory EEG add to the picture?

Abstract

Objective/background: Disrupted sleep can be a cause and a consequence of affective experiences. However, daily longitudinal studies show sleep assessed via sleep diaries is more consistently associated with positive and negative affect than sleep assessed via actigraphy. The objective of the study was to test whether sleep parameters derived from ambulatory electroencephalography (EEG) in a naturalistic setting were associated with day-to-day changes in affect.

Participants/method: Eighty adults (mean age = 32.65 years, 63% female) completed 7 days of affect and sleep assessments. We examined bidirectional associations between morning positive affect and negative affect with sleep assessed via diary, actigraphy, and ambulatory EEG.

Results: Mornings with lower positive affect than average were associated with higher diary- and actigraphy-determined sleep efficiency that night. Mornings with higher negative affect than average were associated with longer actigraphy-determined total sleep time that night. Nights with longer diary-determined total sleep time, greater sleep efficiency, and shorter sleep onset latency than average were associated with higher next-morning positive affect, and nights with lower diary-determined wake-after-sleep-onset were associated with lower next-morning negative affect. EEG-determined sleep and affect results were generally null in both directions: only higher morning negative affect was associated with longer rapid eye movement (REM) sleep that night.

Conclusions: Self-reported sleep and affect may occur in a bidirectional fashion for some sleep parameters. EEG-determined sleep and affect associations were inconsistent but may still be important to assess in future studies to holistically capture sleep. Single-channel EEG represents a novel, ecologically valid tool that may provide information beyond diaries and actigraphy.

Keywords: Actigraphy; Electroencephalography; Longitudinal; Negative affect; Positive affect; Sleep diary.