Impacts of short sleep and extended wakefulness on vigilant performance decline were studied by BWH researchers and published in PNAS.
"If somebody is routinely awake for more than 18 hours daily, then they are also routinely sleeping for less than six hours daily. Therefore, it was unknown whether any decline in vigilance or other functions was due to the extended wakefulness or restricted sleep," said senior author Elizabeth B. Klerman, MD, PhD, from the Division of Sleep and Circadian Disorders, Department of Medicine at BWH. "We found that chronic short sleep duration, even without extended wakefulness, resulted in vigilant performance impairments."
By placing nine healthy participants on a 20-hour "day" during a 32-day inpatient protocol, researchers were able to separate the impact of chronic short sleep from any extended wakefulness. The participants were restricted to 4.67 hours of sleep and 15.33 hours of wakefulness for each 20-hour "day"; this corresponds to approximately 5.5 hours of sleep on a 24-hour day. Eight healthy controls were allowed to sleep 6.67 hours and have 13.33 hours of wakefulness per 20-hour "day", the equivalent of sleeping 8 hours in a 24-hour day. As 15.33 hours of wakefulness is not considered extended wakefulness, but 4.67 hours of sleep is considered short sleep, any performance impairments were considered due to the short sleep itself.