Gaby
A sleep strategy for staying alert on night shifts comes from Japan, a country known for long working hours. Professor Sanae Oriyama from Hiroshima University proposed a method for spacing short sleep periods during nighttime work to help maintain energy. These recommendations could also help new parents who are awake at night.
Oriyama tested 30-, 90-, and 120-minute sleep intervals during a simulated 16-hour night shift. She found that combining a 90-minute sleep with a 30-minute nap was the most effective way to stay alert and reduce fatigue. By comparison, a single 120-minute sleep was the least effective at fighting drowsiness.
The study involved 41 volunteers. Fifteen participants did not sleep at all during the simulated shift, 14 slept for 120 minutes, and 12 took naps of 90 and 30 minutes during the shift.
During the experiments, volunteers performed various tasks every hour. Researchers also asked participants to rate their fatigue. Those who napped only once during the night reported feeling drowsy around 4:00 a.m., while those who slept in two intervals reported drowsiness around 6:00 a.m.
Participants in all groups reported drowsiness from 4:00 a.m. to 9:00 a.m., but the double-nap group experienced less intense sleepiness during that window.
Staying awake at night harms health, but some jobs make it unavoidable — for example, emergency medical staff. In Japan, nurses are typically allowed to sleep for up to two hours during a 16-hour night shift. Oriyama’s sleep schedule could also be useful for workers in other fields and for parents who are awake at night with infants.
The findings were published in the journal Science Advances.
