People sleep longer during early and late adulthood, while middle-aged persons sleep for a shorter duration, according to a new study published in the journal Nature Communications.¹ The sleep patterns also varied between countries.

This study analysed data of self-reported sleep duration in 730,187 participants from 63 countries obtained from the Sea Hero Quest project. It is a mobile video game developed to evaluate the spatial navigation ability of people and serves as an aid to research in Alzheimer’s disease. The study participants were also assigned questionnaires related to their sleep and other demographic questions besides the tasks assigned to assess navigational ability.

Results showed that the average duration of sleep per night was an average of 7.01 hours. The duration was longer in women by 7.5 minutes. Younger participants, minimum age 19 years, slept the longest. The sleep duration decreased in the 20s and early 30s. It then plateaued (age 33) until the early 50s (age 53 years). From here, the duration was found to increase again until 70 years of age, when it became similar to that seen during early adulthood. This pattern was observed to be similar for both men and women, different countries and also across education levels.

Participants from the Eastern European countries such as Albania, Slovakia, Romania and the Czech Republic slept the longest with 20 to 40 minutes of extra sleep per night, while among those from South East Asian countries including Malaysia, Philippines and Indonesia, the sleep duration was a little less than the average. People who lived near the equator slept for shorter durations.

Duration of sleep had no effect on navigational ability in the majority of the study population, except the age group 54-70 years, in whom cognitive ability was seen to have an inverted u-shape relationship with reported sleep duration. The optimal sleep duration in this age group was 7 hours.

This study displays the changes in sleep patterns in the lifetime of an individual and also highlights that the average sleep duration differed between countries. Three phases have been identified: early adulthood (19-33 years), mid-adulthood (34-53 years) and late adulthood (≥54 years). No differences in sleep patterns were seen for gender, educational status. In the third phase, the optimal cognitive performance was noted after 7 hours of sleep. Being engaged in one’s occupation and taking care of children may be the reasons for the reduced sleep duration during mid-life, according to the authors.

Reference

1. Coutrot A, et al. Reported sleep duration reveals segmentation of the adult life-course into three phases. Nat Commun. 2022 Dec 13;13(1):7697. doi: 10.1038/s41467-022-34624-8.