As any bleary-eyed new parent can attest, it’s hard to be chipper after a sleepless night.
A recent study by researchers at John Hopkins University School of Medicine found people whose sleep was interrupted multiple times experienced worse moods than those who simply slept fewer hours.
For three consecutive nights, researchers randomly subjected 62 healthy men and women to one of three sleep experimental conditions: forced awakenings, delayed bedtimes, or uninterrupted sleep. Before bedtime each night, they used a mood assessment questionnaire to gauge each subject’s mood.
After the first night participants who had been subjected to eight forced awakenings and those who had experienced delayed bedtimes showed similar low positive mood and high negative mood. After the second night, however, significant differences emerged. The group that was awakened multiple times in the night experienced a 31 percent decline in positive mood compared with the first day, while the delayed bedtime group experienced only a 12 percent decline.
“When your sleep is disrupted throughout the night, you don’t have the opportunity to progress through the sleep stages to get the amount of slow-wave sleep that is key to the feeling of restoration,” says Patrick Finan, Ph.D., an assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine and the lead author on the study, which was published in the November issue of the journal Sleep.
Interrupted sleep not only reduced subjects’ energy levels but also their feelings of sympathy and friendliness. The study also suggests that the effects of interrupted sleep on positive mood can be cumulative since differences emerged after the second night and continued after the third night.
The study may have implications for people who suffer frequent interruptions in sleep, including new parents, on-call health workers, and people who suffer from insomnia, a condition that affects about 10 percent of the U.S. adult population. Although the study was conducted on healthy subjects with generally normal sleep experiences, frequent awakenings are one of the most common symptoms among people with insomnia.
For more information about sleep disorders and sleep studies, contact the St. Elizabeth Healthcare Sleep Disorders Centers.
