Investigators from Harvard Medical School and Beth Israel Deaconess Medical Center in Boston, Massachusetts found that trimming sleep time in the first half of the night was associated with better performance and mood the next day compared with going to bed early and getting up after 4 hours.
Sleep deprivation has been shown to have harmful effects on health and cognitive performance. Led by Rammy Dang, the investigators tested whether early or late short sleep provides better functioning in a convenience sample of 52 healthy adults ages 20 to 30 years old.
After two baseline “habituation” nights in a sleep lab where participants had the opportunity to sleep for 8 hours (11 PM to 7 AM), they were required to adhere to two different 4-hour sleeping schedules over 3 consecutive nights.
In the early sleep (ES) protocol, participants slept from 11:00 PM to 3:00 AM and in the late sleep (LS) protocol, they slept from 3:00 AM to 7:00 AM. The researchers used polysomnography (PSG) to record electrophysiology of participants during wake and sleep periods and gathered subjective and neurobehavioral data.
Results showed that participants felt worse after the ES protocol, reporting feeling significantly more lonely (P < .001) and less carefree (P = .007). After the ES protocol, they also performed significantly worse on the psychomotor vigilance task (PVT) used to assess vigilant attention during the waking hours. However, there were no differences in sleep electrophysiology.
Reached for comment, Neomi Shah, MD, associate professor of medicine, pulmonary, critical care and sleep medicine at the Icahn School of Medicine at Mount Sinai in New York City, said, “This is an interesting and important [study] as it helps us understand the potential impact of sleep loss on emotional health and vigilance/performance.”
“Typically, the second half of the night has more REM sleep. According to the abstract, the PSG data did not differ in the two groups, suggesting that the amount of REM sleep was similar. However, given the significant differences in emotional health and well-being and vigilance, perhaps the timing of REM sleep may be just as important as the amount,” Shah told Medscape Medical News.
The study was supported by the National Institutes of Health. Dang and Shah have disclosed no relevant financial relationships.