Determinants of sleep quality in the healthy aged: the role of physical, psychological, circadian and naturalistic light variables

Ageing is associated with a decrease in the quality of night-time sleep with 30% of aged persons experiencing chronic insomnia. Treatment of insomnia typically involves the use of hypnotic medications and these have been associated with a range of negative outcomes in this population cohort. The development of age-related insomnia has been linked, in part, to changes in the strength of the circadian regulation of sleep, these changes typically leading to increased fragmentation of the sleep-wake cycle. Management of insomnia may therefore be linked to strengthening of these regulatory control mechanisms. Previous research has indicated that both daily activity levels and ambient light exposure may act as zeitgebers to consolidate sleep-wakefulness cycles. The current study utilised a naturalistic design to explore the relationship between light, activity and night-time sleep quality amongst a sample of 33 healthy aged subjects. Findings demonstrated a significant positive relationship between activity and sleep quality. Ambient light was also shown to have a significant impact on night-time sleep though the study identified a critical exposure threshold of 3000 lux. Factor analysis demonstrated the independent contribution of these two variables to subsequent sleep quality. The findings of the current study identify the potential for the development of non-pharmacological treatment strategies for insomnia in aged people.