The National Institutes of Health describes chronic insomnia as a condition that occurs three or more nights every week, lasts over three months, and isn't caused by other health disorders. A wide array of previous research has linked a lack of sleep with many different health problems like cardiovascular disease, pain, dementia, mental health disorders, or digestion problems. Sleeplessness can come with these problems or make them worse. There is even a rare genetic disorder in which insomnia becomes a fatal condition.
It's thought that about a third of American adults don't get enough sleep. New research reported in the American Journal of Physiology - Heart and Circulatory Physiology has suggested that when an otherwise healthy person's sleep is chronically limited, their heart rhythms become disrupted.
"We really have to look at sleep as a major pillar of our overall health just like we look at physical activity, exercise, and nutrition," said corresponding study author Jason Robert Carter, Ph.D. of Montana State University.
In this study, 35 healthy men and women were placed into one of two categories; one group was regularly getting a normal night of sleep, defined in this work as at least seven hours, while the other group were short-sleepers who tended to get fewer than seven hours of sleep a night. Questionnaires were employed so the participants could self-report information about their sleep habits, and at-home monitors were used to check for disrupted breathing during sleep. The volunteers also slept overnight once in a sleep lab so they could be carefully monitored, and were followed up on at home with a wrist sensor.
The researchers compared the heart rates of the people in the different groups as they slept, focusing on periods when spikes in brain activity occurred, which are called spontaneous cortical arousals (CA). Participants in both groups had comparable numbers of CAs during sleep, but the short-sleepers took longer to return to their normal heart rate after a CA compared to normal sleepers. The study author suggested that this indicates that people who don't get enough sleep chronically are experiencing dysregulation in their cardiovascular system that is disrupting their heart rhythms.