Chronotype predicts positive affect rhythms measured by ecological momentary assessment

Area of Science:

• Chronobiology
• Affective Science
• Sleep Medicine

Background:

• Evening chronotype correlates with delayed circadian rhythms and is associated with depression.
• Altered positive affect (PA) rhythms may mediate the link between evening chronotype and depression severity.
• Understanding chronotype-PA relationships may illuminate depression etiology.

Purpose of the Study:

• Investigate the relationship between chronotype and PA rhythms.
• Examine the role of sleep timing and social jet lag (SJL) in this association.
• Determine if PA rhythms are delayed and blunted in evening types.

Main Methods:

• Healthy adults (n=408) completed chronotype and affect questionnaires.
• Ecological momentary assessment (EMA) measured positive and negative affect hourly over workdays and non-workdays.
• Actigraphy collected sleep data; cosinor multilevel modeling analyzed PA rhythms (amplitude, acrophase).

Main Results:

• Evening chronotype individuals exhibited lower PA amplitudes and later workday acrophase times compared to morning types.
• Social jet lag (SJL) did not mediate the relationship between chronotype and PA rhythms.
• Findings suggest evening chronotype is associated with blunted and delayed PA rhythms.

Conclusions:

• The association between chronotype and PA rhythms in healthy adults supports the hypothesis that evening chronotype may confer vulnerability to depression.
• Delayed and blunted PA rhythms associated with evening chronotype may be a key factor in depression development.
• Daily PA measurement is crucial for understanding depression in individuals with evening chronotypes.