BMJ Group Nov 26 2024 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