Lok, R., Weed, L., Winer, J., & Zeitzer, J. M. (2024). Perils of the nighttime: impact of behavioral timing and preference on mental health in 73,888 community-dwelling adults.Psychiatry Research,337, 115956.
Key TakeawaysThe primary methods of investigating the impact of behavioral timing and preference on mental health included analyzing data from 73,888 community-dwelling adults in the UK Biobank, using accelerometry to determine behavioral timing and questionnaires to assess chronotype.Factors like chronotype (morning, intermediate, or evening preference), timing of behavior (early, intermediate, or late), and the alignment between chronotype and behavior significantly affect the prevalence and likelihood of mental health disorders, including depression and generalized anxiety disorder.Limitations include reliance on self-reported sleep duration, use of ICD-10 codes for disorder prevalence, and a predominantly Caucasian sample.This study is universally relevant as it highlights the importance of sleep timing, beyond just sleep duration, in mental health outcomes. The findings suggest that going to sleep before 1 AM, regardless of chronotype, may promote overall well-being.
Key Takeaways
Rationale
Previous research has shown associations between evening preference and mental health disorders (Díaz-Morales & Sánchez-Lopez, 2008; Konttinen et al., 2014; Lemoine et al., 2013), particularly in individuals with depression (Chan et al., 2014).
However, the impact of the alignment between chronotype and actual sleep timing on mental health has not been thoroughly investigated in a large-scale study.
Method
The study utilized data from the UK Biobank, a large community-dwelling cohort of middle-aged and older adults.
Participants wore wrist-worn triaxial accelerometers for seven consecutive days to determine their behavioral timing. Chronotype was assessed through a questionnaire.
Mental health disorders were identified using ICD-10 codes. The study examined the impact of chronotype, behavioral timing, and the alignment between the two on mental, behavioral, and neurodevelopmental disorders (MBN), depression, and generalized anxiety disorder (GAD).
Procedure
Participants wore accelerometers for seven consecutive days, 24 hours per day.
They also completed questionnaires providing information on demographics, health status, and lifestyle. Chronotype was determined based on a single question about morning or evening preference.
Sample
The final sample included 73,888 participants from the UK Biobank. The sample was 56% female, with a median age of 63.5 years.
The median Body Mass Index was 26.0, and the median Townsend Deprivation Index was -2.45. The majority (97.1%) of the sample was self-reported to be Caucasian.
Measures
Statistical measures
The study usedchi-square teststo examine the frequency of disorder diagnosis. Generalized linear models were used to determine the likelihood of having a disorder. Survival analyses (Cox proportional hazards analysis) were conducted to determine differences in disease-free intervals.
All analyses were adjusted for demographic factors, self-reported sleep duration, and sleep-wake stability. Statistical significance was corrected for multiple tests using a Bonferroni correction.
Results
The study did not explicitly state hypotheses, but the main results include:
Insight
The key finding of this study is that for all chronotypes, having an earlier sleep schedule is better for mental health. This is particularly informative because it challenges the common belief that aligning sleep patterns with one’s preferred sleep time (chronotype) is always best for mental health.
These findings suggest that the timing of sleep, independent of sleep duration or chronotype, plays a crucial role in mental health. This opens up new avenues for research into the mechanisms underlying this relationship.
For example, future studies could investigate how late-night wakefulness affects decision-making processes or alters prefrontal cortex functioning, potentially leading to mood disturbances.
The next steps in the field could include:
Strengths
Limitations
These limitations may affect the precision of sleep duration estimates, the accuracy of mental health disorder prevalence, and the generalizability of findings to more diverse populations. The short follow-up period may have underestimated the long-term impact of sleep timing on mental health.
Implications
The results of this study have significant implications for research, clinical practice, and public policy. The finding that going to sleep before 1 AM, regardless of chronotype, is associated with better mental health outcomes provides a clear, actionable message for public health initiatives.
For clinical practice, these results underscore the importance of considering sleep timing, not just sleep duration, when assessing and treating mental health disorders. Clinicians may need to pay more attention to patients’ sleep schedules and consider interventions that aim to shift sleep timing earlier, even for patients who identify as “night owls.”
In terms of research, these findings highlight the need for more studies investigating the mechanisms underlying the relationship between late sleep timing and mental health. This could lead to new targets for intervention in mental health disorders.
From a public policy perspective, these results could inform discussions about work schedules, school start times, and other societal factors that influence sleep timing. Policies that promote earlier sleep times could potentially have significant public health benefits.
References
Primary reference
Other references
Chan, J.W.Y., Lam, S.P., Li, S.X., Yu, M.W.M., Chan, N.Y., Zhang, J., & Wing, Y.-K. (2014). Eveningness and insomnia: independent risk factors of nonremission in major depressive disorder.Sleep, 37(5), 911-917.
Díaz-Morales, J.F., & Sánchez-Lopez, M.P. (2008). Morningness-eveningness and anxiety among adults: a matter of sex/gender?Personality and Individual Differences, 44(6), 1391-1401.
Konttinen, H., Kronholm, E., Partonen, T., Kanerva, N., Männistö, S., & Haukkala, A. (2014). Morningness–eveningness, depressive symptoms, and emotional eating: a population-based study.Chronobiology International, 31(4), 554-563.
Lemoine, P., Zawieja, P., & Ohayon, M.M. (2013). Associations between morningness/eveningness and psychopathology: an epidemiological survey in three in-patient psychiatric clinics.Journal of Psychiatric Research, 47(8), 1095-1098.
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Olivia Guy-Evans, MSc
BSc (Hons) Psychology, MSc Psychology of Education
Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.
Saul McLeod, PhD
BSc (Hons) Psychology, MRes, PhD, University of Manchester
Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.
