Night shift survival: Ideal nap strategy for new parents and workers

The impact of short and long naps on alertness and performance: A reanalysis.


This study looks at new parents and night shift workers‘ difficulties. They often have to stay awake at night. The study wants to find the best ways to take naps that keep them sharp and help them do well when they have to work at night.

A new study looked at Hiroshima University how to stay awake and alert during a 16-hour night shift. It found that taking two naps is better than one long nap. First, a 90-minute rest and then a quick 30-minute nap later help prevent drowsiness and fatigue. This strategy can also be helpful for new parents. 

The study was published in the journal Scientific Reports. According to the study’s author, Professor Sanae Oriyama, a 90-minute nap helps with long-term performance. In contrast, a 30-minute nap keeps you alert and less tired for faster reactions. Using both nap lengths can improve efficiency and safety during early morning work.

Working night shifts is standard in critical fields like healthcare but can harm health and job performance. Our bodies are naturally alert during the day and sleepy at night. This can lead to mistakes and accidents, especially in healthcare. 

To combat this, workers often take naps. In Japan, nurses can nap for up to two hours during 16-hour night shifts. A study wanted to find the best nap schedule to fight sleepiness and cognitive decline during these long shifts and see how it affects sleep quality.

Oriyama revisited earlier studies she worked on to see how naps affect alertness and performance during a simulated overnight shift from 4 p.m. to 9 a.m. The first study was in 2012 with one nap, the second in 2014 with two naps, and the third in 2018 with no nap.

She hopes to use these findings to choose the proper naps for different types of work and times of day to reduce drowsiness fatigue, and maintain good performance.

Her research showed that those who took a 120-minute nap until midnight felt more tired starting at 4 a.m. and stayed tired until the end of their shift. However, those who had two naps – one for 90 minutes until midnight and another for 30 minutes until 3 a.m. – stayed alert until 6 a.m. 

She also suggested adding a 30-minute nap between 5-6 a.m. because tiredness tends to increase from 7-8 a.m.When it comes to feeling tired, all nap groups felt more tired from 4-9 a.m., but the two-nap group felt it less intensely than the others.

Oriyama said, “During a night shift that, for example, lasts from 4 p.m. to 9 a.m. the next morning, a split nap of 90 minutes and 30 minutes, ending at 12 a.m. and 3 a.m., respectively, is thought to be more effective than a 120-minute monophasic nap ending at midnight when tasks requiring quick responses to maintain a high level of safety are scheduled between 2 a.m. and 9 a.m.”

Both long and short naps didn’t improve cognitive performance. However, if people took a long time to fall asleep during the 90-minute nap, they did worse on a math test. It takes 90 minutes to complete a sleep cycle; waking up before that can make you feel groggy. On the other hand, previous studies show that naps of 30 minutes or less can increase alertness and energy.

The study also found that the timing of your nap matters. Napping later is better for staying awake, but waiting too long can affect your focus as your body’s sleep drive builds up. So, the best time and schedule for naps during long night shifts still need more research.

Oriyama believes her findings can help night shift workers and new parents dealing with sleep deprivation from caring for infants.

The study involved 41 women in their 20s who underwent a 16-hour night shift simulation in a controlled environment. They took math tests, and their temperature, drowsiness, fatigue, heart rate, and blood pressure were monitored. They also had scheduled nap times in a darkened room, and their sleep quality was measured during those naps.

For new parents and night shift workers seeking strategies to stay alert during all-nighters, a 30-minute nap could be the key to maintaining performance. This study provides valuable insights for individuals navigating challenging schedules. It highlights the importance of selecting a suitable nap duration to optimize cognitive functioning during nocturnal duties.

Journal Reference:

  1. Oriyama, S. Effects of 90- and 30-min naps or a 120-min nap on alertness and performance: reanalysis of an existing pilot study. Scientific Reports. DOI: 10.1038/s41598-023-37061-9.
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