An abnormal sleep pattern and lack of sleep may increase the risk for heart disease, especially for shift workers, a small study reports.
Dr. Daniela Grimaldi, lead author on the study, says, “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.” A research assistant professor at Northwestern University in Chicago, Grimaldi adds,
When our sleep-wake and feeding cycles are not in tune with the rhythms dictated by our internal clock, circadian misalignment occurs.
The research found that shift workers who “who are chronically exposed to circadian misalignment, might not fully benefit from the restorative cardiovascular effects of nighttime sleep following a shift-work rotation.”
The study followed 26 healthy people, between the ages of 20 to 39, who only had five hours of sleep for eight days with either fixed bed times or bed times delayed by 8.5 hours on four of the eight nights.
During the day, a higher heart rate was recorded in both groups, greater in those who had sleep deprivation combined with later bed times. There was also an increase in levels of the stress hormone norepinephrine in the group that was sleep-deprived and had delayed bed times.
Norepinephrine is a hormone that can narrow blood vessels, increase blood pressure and expand the windpipe, the study said.
The research further stated that sleep deprivation and delayed bed time were also linked to reduced heart rate variability at night and reduced vagal activity during the phases of deep sleep that normally restore heart function. The main effect of the vagal nerve on the heart is to lower heart rate.
Shift workers are encouraged to eat a healthy diet, get regular exercise and sleep more to protect their hearts and prevent increased risks for heart diseases.
The study was published in the journal Hypertension.