A recent US research study sheds further light on the sleep patterns of night-shift workers.
- Scroll down to read the article or download a print-friendly PDF here
Having an evening sleep before a night shift and having enhanced lighting during the second half of the shift improved the performance of shift workers over the age of 50, according to a recent US research study (Chinoy et al, 2016).
The long-term ill effects of shift work on health are well established: cardiovascular disease, cancer, early mortality and reduced quality of life, alertness and performance. The risks are greater for those in older age groups.
Strategies to minimise these risks have focused on using circadian rhythm measures such as manipulating sleep timing and exposure to light. For example, having an evening sleep maintains the usual relationship between sleep and work (which is that work begins shortly after waking). However, many shift workers traditionally sleep immediately after work.
In this study, researchers tested the hypothesis that a scheduled evening sleep and enhanced lighting in the latter part of a night shift would improve alertness and performance compared with ad-lib sleep timing and usual lighting.
Because of the increased risks in older age groups, the researchers decided to focus on older workers. Eighteen adults aged 50-65 (average 57 years) were recruited and followed a protocol of four day shifts followed by three night shifts. Participants in the treatment group were instructed to sleep eight hours from lunchtime onwards and had enhanced indoor lighting at work from 3-7am. In the control group, participants were allowed to sleep whenever they wanted in the day and did not have the enhanced lighting at night.
Participants had hourly cognitive and attention testing, and also self-rated their sleepiness during their night shifts. Bed and wake times were determined from voicemail call-ins and sleep diaries. Melatonin levels in saliva were measured.
Compared with day-shift workers, alertness and attention declined in the first night shift for all participants. However, alertness and attention improved in the second and third night shifts in the treatment group while remaining lower in the control group. By the third night shift, alertness in the treatment group had improved to day-shift level but continued to decline in the control group.
The researchers said that night-shift workers would benefit from not sleeping immediately after work, sleeping instead in the afternoon. They noted that this pattern would be easier for older workers, as these are less likely to have family demands that would make it difficult.
The researchers called for further research to separate the factors of evening sleeping and enhanced lighting. Testing different evening sleep patterns would also help, as the length of the sleep in this study (eight hours) and its timing may be a barrier for some shift workers.
Kathryn Godfrey, practice and learning editor, Nursing Times
Box 1. What we already know
- Shift work has long-term negative effects on health and quality of life
- Older age increases the risks
- Sleeping in the morning builds greater pressure to sleep
- Evening sleep and enhanced lighting improve alertness and performance in young adults
Box 2. What this research adds
- Evening sleep and enhanced lighting improved alertness and performance in older adults
- Further research is needed to isolate the impact of individual factors and variations in sleep patterns
Box 3. What this means for nursing - An expert view
Professor Peter Griffiths is chair of health services research, University of Southampton, NIHR CLAHRC (Wessex).
“Night shift work is an inevitable part of the job for many nurses. This study highlights the importance of sleep and rest patterns to help adapt to work at night and avoid the negative effects of fatigue, which can affect nurses’ wellbeing and the quality and safety of the care they provide. Fast rotating night shifts (short runs of night shifts) are linked to a higher risk of errors than longer runs, where more adaptation occurs.
“The study is on quite a small scale, and participants undertook ‘simulated’ shift work, so the results need to be interpreted with some caution. It is not clear whether the benefits came about because of evening sleep, the raised lighting levels at the end of the shift or indeed simply the increased total amount of sleep achieved. While this study only involved people over 50 years old, the results mirror those of similar studies on younger people.
“Raised lighting levels might not be possible on hospital wards at night, but the idea of delaying sleep after a night shift until the evening might be practical for some nurses and could be worth trying. Perhaps more importantly, this study should remind all shift workers of the importance of getting adequate sleep between shifts and the substantial body of research showing the negative impact of fatigue on the performance of shift workers, including nurses. The best approach to adapting to night shifts remains uncertain, but establishing good sleep patterns is an essential part of it.
Suggested further reading: Dall’ora C et al (2016) Characteristics of shift work and their impact on employee performance and wellbeing: a literature review. International Journal of Nursing Studies; 57: 12-27.
Chinoy ED et al (2016) Scheduled evening sleep and enhanced lighting improve adaptation to night shift work in older adults. Occupational and Environmental Medicine; 73: 869-876.