'Therefore, it was unknown whether any decline in vigilance or other functions was due to the extended wakefulness or restricted sleep. 'We found that chronic short sleep duration, even without extended wakefulness, resulted in vigilant performance impairments.' The participants were restricted to 4.67 hours of sleep and 15.33 hours of wakefulness for each 20-hour 'day'. Eight healthy 'controls' were allowed to sleep six hours 40 minutes and have 13 hours 20 minutes of wakefulness per 20-hour 'day', the equivalent of sleeping eight hours in a 24-hour day. As 15 hours and 20 minutes of wakefulness is not considered extended wakefulness, but four hours 40 minutes of sleep is considered short, the researchers said any performance impairments were considered due to the short sleep itself.

Source: Daily Mail May 21, 2018 18:56 UTC