Latest evaluation of pilot studies on night shift naps conducted from 2012 to 2018 revealed the perfect snoozing strategy that may help counteract drowsiness and fatigue during a 16-hour overnight duty. The findings can even profit latest parents.

Reanalysis of knowledge showed that when staying up all night, scheduling two nap sessions -; a 90-minute one followed by a fast 30-minute shut-eye later -; is the optimal alternative over a single 120-minute snooze in pushing aside drowsiness and fatigue. The study was published within the journal Scientific Reports.

A 90-minute nap to keep up long-term performance and a 30-minute nap to keep up lower fatigue levels and fast reactions, as a strategic combination of naps, could be useful for early morning work efficiency and safety.”

Sanae Oriyama, study sole creator, nursing science professor at Hiroshima University’s Graduate School of Biomedical and Health Sciences

Shift work is a norm in emergency sectors reminiscent of healthcare where round the clock access to services could be life-saving. And dealing double shifts on nontraditional hours is not unheard of amongst medical professionals. Nonetheless, night shift work can be known to extend the danger for sleep-related physical and mental health disorders and impair job performance.

Through the daytime, our light-sensitive internal clock prompts wakefulness. The alternative happens at nighttime when alertness dims as our biorhythm readies to modify off, elevating the likelihood of errors and accidents. Within the medical field, this may increasingly inadvertently result in serious harm to patients or to oneself. Naps are frequently taken by shift employees to offset disruptions to the body clock.

In Japan, nurses are typically allowed to sleep as much as two hours during 16-hour night shifts. Oriyama wanted to seek out out which napping schedule is one of the best in fighting off sleepiness and diminished cognitive function during such grueling work hours. And while at it, work out how sleep quality aspects in.

Single versus split naps

Oriyama reexamined past pilot studies she co-authored to match alertness and cognitive performance after taking a nap and throughout a simulated 4 p.m. to 9 a.m. shift. The one-nap condition experiment was conducted in 2012, the two-nap in 2014, and the no-nap in 2018.

“I need to have the opportunity to mix multiple naps, depending on the sort of work and time of day, and select naps which are effective at reducing drowsiness, fatigue, and maintaining performance,” she said.

She found that those that took a single 120-minute nap ending at midnight experienced worse drowsiness as soon as 4 a.m. and lasted until the tip of the shift. Nonetheless, participants who scheduled two naps -; the 90-minute one lasting until midnight and the 30-minute one ending at 3 a.m. -; staved off drowsiness until 6 a.m. Oriyama suggested adding an additional half-hour of shut-eye between 5-6 a.m. provided that drowsiness might shoot up from 7-8 a.m.

As for fatigue, although all nap groups expressed significantly heightened levels of it from 4-9 a.m., the two-nap group experienced it at an intensity lower than the remainder.

“During an evening shift that, for instance, lasts from 4 p.m. to 9 a.m. the following morning, a split nap of 90 minutes and half-hour, ending at 12 a.m. and three a.m., respectively, is considered more practical than a 120-minute monophasic nap ending at 12 a.m. when tasks requiring quick responses to keep up a high level of safety are scheduled between 2 a.m. and 9 a.m.,” Oriyama said.

Finding one of the best nap length, timing

Each the only and split naps didn’t lead to improved cognitive task performance. Nonetheless, Oriyama noted that those that took longer to go to sleep through the 90-minute nap session showed poorer scores within the Uchida-Kraepelin test (UKT), a timed basic math exam meant to measure speed and accuracy in performing a task.

It takes 90 minutes to finish a full sleep cycle. And waking up before it’s finished could exacerbate sleep inertia, the grogginess and disorientation felt upon first waking up. Similarly, the study found that if total sleep time is prolonged, fatigue and drowsiness could also increase.

Meanwhile, past research showed that a nap of half-hour or less could help boost vigilance, alertness, and energy levels.

The study also found that the timing of your nap plays a vital role: the later you are taking it, the stronger it’s in keeping off sleepiness and exhaustion. Nonetheless, delaying it an excessive amount of could interfere together with your focus as your sleep drive builds up.

“Hence, the perfect time for taking a nap and the perfect nap schedule during long night shifts need further elucidation,” Oriyama said.

Helpful for brand new parents, too

Oriyama said her findings is also helpful to latest parents.

“The outcomes of this study could be applied not only to nighttime shift employees but in addition to reduce sleep deprivation fatigue in moms raising infants.”

A complete of 41 females of their 20s participated within the studies. Research participants were invited to a windowless and soundproofed laboratory for a 16-hour night shift simulation. The room temperature was kept at a cushty 26 degrees Celsius and lightweight intensity above work desks was set at 200 lux, the everyday illuminance level in offices. All took the UKT each hour. Their hourly temperature, self-reported drowsiness and fatigue levels, heart rate, and blood pressure were also measured. After the tests, participants have free time to do anything they need on their desks like reading, drawing, or drinking water. Through the scheduled nap time, they moved to a neighboring bedroom where they were allowed to darken the sunshine in accordance with their preference. Their sleep parameters were measured during this time.

Source:

Journal reference:

Oriyama, S., et al. (2023) 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.org/10.1038/s41598-023-37061-9.