A recent article published in Chronobiology International examines the role of napping in helping with work performance in night shift work.
There exists an association between night shift work and adverse health effects. When the body is forced to stay awake and work throughout the night, it coincides with the internal body clock and environmental signals, such as the lack of sunlight. Our bodies have a circadian rhythm, which is commonly described as the internal body clock. This internal body clock regulates bodily processes in a 24-hour cycle. These circadian rhythms control various aspects ranging from sleepiness to heart rate, and even stress levels.
Naps Have Drawbacks
Accordingly, studies demonstrate the occurrence of workplace accidents is significantly higher during the night and early morning. Thus, there is a strong basis for the creation of measures to support shift workers. Some groups have examined the effectiveness of napping and observed beneficial effects from short naps during shifts longer than 12 hours. However, there are drawbacks to naps, as longer naps can cause drowsiness and impact normal sleep schedules. There is also the risk of an interrupted nap, which may affect alertness and performance. Nonetheless, there is a need to further understand how naps can help shift work and one South African group specifically examines the effectiveness of elongated napping for shorter eight-hour shifts in a recent Chronobiology International article.
Volunteers in Good Health Recruited
In this study, 33 student volunteers in good health were recruited to perform cognitive and motor tests in eight-hour shifts over a period of five days. Participants were divided into three groups: no nap group, which had 10 p.m. to 6 a.m. shifts; nap early group, which had 8 p.m. to 8 a.m. shifts with a 3-hour nap at 12 am; and the nap late group, which had 12 am to 12 pm shifts with a 3-hour nap at 4 am.
The results showed that the performance of a task involving the threading of beads did not vary among the three groups, but there was an observed decrease in performance in each group as time progressed during the shifts. Performance of reaction time and visual perception tasks also did not vary between the groups. Interestingly, the nap late group had worse performance on a “working memory digit recall test” that required participants to memorize a series of seven numbers. Moreover, the nap late group reported longer naps and the groups containing a nap period felt less sleepy than the group without naps.
The Timing of Naps Matters
This study overall highlights the influence of napping on memory performance and sleepiness, in addition to the nuances of nap and shift times. Elongated naps appear to help reduce sleepiness and could be implemented in later night shift roles. However, the results demonstrate that the timing of naps can have variable effects on memory performance, so extensive studies on optimal nap timing will have to be performed to further optimize this strategy to improve shift work performance.
Written by Branson Chen, BHSc
Reference: Davy J, Göbel M. The effects of extended nap periods on cognitive, physiological and subjective responses under simulated night shift conditions. Chronobiology International. 2017 Nov 2:1-9.