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