Pulling an all-nighter for an exam? Or do you work night shifts that you just can’t avoid? Well, researchers have revealed the optimal napping method to help combat fatigue during a 16-hour overnight duty.
The research looked at data from pilot studies on night shifts conducted from 2012 to 2018 and found that the analysis could also be the key to providing relief for sleep-deprived mothers and fathers.
The team found that scheduling two nap sessions – a 90-minute nap followed by a quick 30-minute nap later – is the optimal choice over a single 120-minute rest for delaying fatigue and sleepiness.
“A 90-minute nap to maintain long-term performance and a 30-minute nap to maintain lower fatigue levels and fast reactions, as a strategic combination of naps, can be valuable for early morning work efficiency and safety,” said study author Sanae Oriyama, a nursing science professor at Hiroshima University’s Graduate School of Biomedical and Health Sciences.
The study, published in the journal Scientific Reports, found that many professions, including those in emergency sectors, have a lot of night shift work which can in turn increase the risk for sleep-related physical and mental health disorders and impair job performance.
When daytime comes, the human body has a light-sensitive internal clock that activates wakefulness, and at night, this pushes the human body towards sleep. Study authors say because of this, the likelihood of errors and accidents during a night shift is elevated.
In the medical field, this may inadvertently lead to serious harm to patients or to oneself, and naps are usually taken by shift workers to offset disruptions to the body clock.
For the study, researchers looked at 41 women in their 20s who underwent a simulated 16-hour shift in a controlled environment, where factors, such as light and temperature, were standardised.
Participants underwent hourly tests, including the Uchida-Kraepelin test (UKT) for assessing task speed and accuracy, and measurements of drowsiness, fatigue, heart rate and blood pressure.
Professor Oriyama found that women who took a single 120-minute nap suffered increased drowsiness from 4am onward.
Those who had two naps, a 90-minute nap followed by a 30-minute nap, postponed their drowsiness until 6am. Researchers suggest adding an extra 30 minutes of shut-eye between 5am and 6am, given that drowsiness might shoot up from 7am to 8am.
All nap participants reported fatigue between 4am and 9am, whereas the dual-nap group reported less intense fatigue.
“During a night shift that, for example, lasts from 4pm to 9am the next morning, a split nap of 90 minutes and 30 minutes, ending at 12am and 3am, respectively, is thought to be more effective than a 120-minute monophasic nap ending at 12am when tasks requiring quick responses to maintain a high level of safety are scheduled between 2am and 9am.,” Professor Oriyama said.
The study also revealed that the duration of the nap plays a crucial role. The later you take it, it will become more difficult to fend off sleepiness and exhaustion. However, delaying it too much could interfere with your focus as your sleep drive builds up.
“Hence, the ideal time for taking a nap and the ideal nap schedule during long night shifts need further elucidation,” Professor Oriyama added.