An irregular sleep-wake cycle is associated with a heightened risk of major cardiovascular events, such as heart attack and stroke, even for those who clock up the recommended nightly hours of shut-eye, finds research published online in the Journal of Epidemiology & Community Health . Most studies looking at the impact of sleep on health have focused on sleep length and less is known about the impact of sleep patterns, in particular the impact of irregular sleep-;defined as variations in the time a person goes to sleep and wakes up. To explore this further, the researchers drew on 72,269 people aged 40 to 79, taking part in the UK Biobank study, none of whom had any history of major cardiovascular events.
They wore an activity tracker for 7 days to record their sleep, the data from which were used to calculate each person's Sleep Regularity Index (SRI) score. People with an SRI score of more than 87 were considered to have a regular sleep pattern, while those with an SRI score of less than 72 were categorised as irregular sleepers. And those whose scores fell between this range were regarded as moderately irregular sleepers.
Incidents of cardiovascular death, heart attack, heart failure, and stroke over the next 8 years were collected from death registries and hospital records and used to calculate the risk of these events for each sleep pattern group. After accounting for a range of potentially influential factors, such as age, physical activity levels, discretionary screen.