New research published in the American Heart Association’s Hypertension journal suggests that insufficient sleep as well as sleep-cycle disruption -- typical of shift workers and chronically sleep-deprived people -- may lead to increased risks for cardiovascular disease.
“In humans, as in all mammals, almost all physiological and behavioral processes -- in particular the sleep-wake cycle -- follow a circadian rhythm that is regulated by an internal clock located in the brain,” Northwestern University Research Assistant Professor Daniela Grimaldi, the lead author, said. “When our sleep-wake and feeding cycles are not in tune with the rhythms dictated by our internal clock, circadian misalignment occurs.”
Researchers restricted the sleep of their 26 participants to five hours over the course of eight days and delayed some participants’ sleep by 8.5 hours for four days, the study's duration. They found that those with the delayed bedtimes had higher levels of heart rate increases and other signs that their sleep wasn’t as restorative as standard sleep schedules and durations.
“Our results suggest shift workers, who are chronically exposed to circadian misalignment, might not fully benefit from the restorative cardiovascular effects of nighttime sleep following a shift-work rotation,” Grimaldi said. “In modern society, social opportunity and work demand have caused people to become more active during late evening hours, leading to a shift from the predominantly daytime lifestyle to a more nocturnal one. Exposure to consecutive days of sleep loss can impair cardiovascular function, and these negative effects might be enhanced when changes in feeding and/or sleep-wake habits lead to a circadian disruption.”