The researchers reported that aging brings degeneration of the circadian pacemaker, a progressive decline in melatonin output and decrease in rhythm amplitude which contributes to increasing sleep fragmentation and waking up earlier in the morning.
Data from a recent study suggests short sleep duration may be associated with male gender, older age, low social status, and high coffee intake.
The study, published by PLOS One, involved a cross-sectional analysis of 82,995 participants in the UK Biobank cohort. The researchers collected sociodemographic and lifestyle data through the use of touch-screen questionnaires from 2007 to 2010.
“Sleep architecture changes with age. During aging, there is a degeneration of the circadian pacemaker, a progressive decline in melatonin output and decrease in rhythm amplitude which contributes to increasing sleep fragmentation and waking up earlier in the morning,” explained the authors. “Additionally, >50% of those older than 65 years of age have chronic sleep complaints, including difficulties in initiating and maintaining sleep. Sleep disturbance is associated with worse physical and mental health, cognitive impairment and falls, but correlation remains debated.”
Wrist-worn accelerometers were used from 2013 to 2015 to measure sleep and physical activity parameters. Additionally, all participants were divided into 5 groups passed on their objective sleep duration per night, according to the study.
Of all participants, 33.5% slept 6 to 7 hours per night. The results also demonstrated that females had longer objective sleep duration than males, while short objective sleep duration (less than 6 hours) was correlated with older age, social deprivation, and high coffee intake. In addition, the study reported that those who slept 6 to 7 hours per night were the most physically active.
“An inverse ‘U-shaped’ relationship between objective sleep duration and physical activity level was also identified suggesting that the most physically active slept between 6—7 hours,” the study said. “All prior UK biobank sleep studies have used the self-reported sleep data. An association between worse cardiometabolic health and impaired task performance with sleep duration <7 hours or >9 hours per night was reported.”
The researchers concluded that male gender, older age, low social status, and high coffee intake is associated with objectively determined short sleep duration. Also, optimal sleep duration for health in those over 60 years old may be shorter than for younger groups.
“This raises the possibility that objectively assessed 6—7 hours of sleep per night may be optimal for health, at least for those aged over 60 years old. Understanding the association with sleep and health could help to design and optimize interventions to targeted groups and therefore reduce the adverse health impact of poor sleep,” concluded the authors.
Zhu G, Catt M, Cassidy S, et al. Objective sleep assessment in >80,000 UK mid-life adults: Associations with sociodemographic characteristics, physical activity and caffeine [published online December 27, 2019]. PLOS One. DOI: doi.org/10.1371/journal.pone.0226220.