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The night shift

Follow the evidence to survive and thrive

Morelock, Skip G. PhD, MPA, RN, NEA-BC

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doi: 10.1097/01.NURSE.0000526889.33176.10
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ONE OF THE MOST IMPORTANT health threats to current and future nurses is the demand that shiftwork places upon nurses, especially those nurses who primarily work the night shift. Most nurses begin their professional careers in hospitals, and many will spend some time in a job where night-shift work is required. Night-shift work has some positive aspects, such as the freedom to schedule activities during the daytime, a work environment generally free from distractions from administrative personnel and visitors, less concern with organizational imperatives and politics, and higher pay. But it also carries some potentially serious health risks. This article explores the possible physical and psychosocial consequences of working the night shift as well as strategies that may help nurses reduce the negative consequences of night-shift work.

Exploring the risks

Research conducted during the past 20 years has led to a growing body of evidence about the hazards of night-shift work. Studies have shown that working all night for as little as three shifts per month is associated with an increased likelihood of developing metabolic syndrome, a fourfold increase in the incidence of vascular events, and an increased chance of developing certain cancers.1-3

Working night shifts for an extended period also has implications for psychosocial health. Night-shift work tends to require a rigid schedule, making it more difficult for night nurses to adapt to last-minute emergencies or family crises, or to enjoy spontaneous activities with family and friends. Accommodating last-minute staffing changes in a hospital is generally more difficult during the night shift than during the normal business day, when more resources are available for reallocation.

Work and family balance may also suffer when a parent is working the night shift. Estryn-Béhar et al. conducted research on work–life–family balance among nurses working in hospitals on several different shifts.4 They found that working the night shift at least six shifts per month resulted in a higher incidence of sick calls and a higher incidence of intent to leave the work setting. Feelings of having inadequate child care while at work was a strong indicator in the intent to leave the work setting. Nightly 12-hour shifts also increased nurses' worries about making mistakes by nearly 50%. Interestingly, these researchers found that even nurses who expressed satisfaction with working the night shift still had a higher incidence of negative physiologic symptoms than their counterparts who worked only 8-hour or 12-hour day shifts.

Effects on physical health

Health risks aren't limited to nurses who work in a hospital environment; similar findings have been demonstrated in other fields that require working around the clock. Begani et al. examined 110 security guards and found that most (84%) suffered at least one ill effect from night-shift work, including gastrointestinal upset, development or exacerbation of sleep disorders, fatigue, and weight gain.5 The authors report that 47% continued to feel these effects after ending night-shift work, suggesting that long-lasting physiologic changes might be slow to revert to baseline. Research is needed about how the body adjusts once the person no longer works nights. Unfortunately, few longitudinal studies have examined the long-term connection between night shift and physical ailments.

Nurses in general may be predisposed to developing obesity, and night-shift nurses in particular may be at higher risk for increased body mass index (BMI).6 Marqueze et al. reported that the difference in weight gain between day- and night-shift workers wasn't significant, but most workers (52%) had reported a weight gain in the past year.7 However, when they tested the variable of smoking, they found a significant difference in self-reported daily smokers between the day and night shifts. In this cohort of nurses, the smoking finding was related to an overall BMI increase.

Using linear regression, these authors also found that night-shift nurses increased their BMI at a significantly higher rate than the day-shift nurses (0.24 kg/m2 for night shift and 0.15 kg/m2 for day shift).7 Smith and Eastman found a smaller, but still statistically significant, difference in the BMI of day- and night-shift nurses.1 Controlling for gender didn't significantly alter the results. Nutritional and dietary irregularities of night-shift nurses appear to be relevant, and the impact of these issues on the health and illness trends in night-shift workers is also a concern.

Working the night shift creates a series of health challenges that can put night workers at greater risk for illness and disease. Preventive health services must be accessed when the night-shift worker would normally be sleeping. Studies questioning the possible health effects of nontraditional sleep patterns have appeared in the literature. In a cohort of RNs and other night-shift workers, Vyas et al. conducted a meta-analysis of physiologic effects of night-shift work.8 They found that night-shift workers experienced a higher incidence of myocardial events and ischemic stroke than the general population. The severity and chronicity of these types of health problems make it essential to determine if altered sleep patterns may be responsible for a predisposition to illness and disease in night workers.

Other studies have suggested that factors other than lack of sleep may be predisposing individuals working the night shift to health issues. Although fatigue may ultimately prove to have some impact, an alternate theory is that interrupting an individual's chronobiologic cycle, with the accompanying alterations in cortisol levels, may be to blame.9 Other somatic events that seem to be linked to extended shift work are irritable bowel syndrome and certain cancers.10,11

In one study, the risk of ischemic strokes was found to increase at a rate of 4% for every 5 years of consecutive night-shift work.8 Nurses who had worked over 15 years on the night shift and had identified themselves as smokers were at the highest risk when compared with nonsmoking night-shift nurses.

Night-shift nurses also seem to be more likely to develop gastrointestinal diseases. Nojkov et al. found that when compared with their day-shift counterparts, night-shift nurses experienced a higher incidence of irritable bowel syndrome and diarrhea.10 Perhaps diet can explain these differences, or other triggers may be involved.

Schernhammer et al. examined breast and skin cancers in female nurses.11 They discovered that the incidence of all types of skin cancers decreased by 14% in the nurses who worked night shift compared with day-shift nurses. Interestingly, the authors didn't find that the lack of exposure to sunlight explained this finding; instead they suggested that lower levels of melatonin may have a protective effect. These authors also researched night-shift work and breast cancer and found a 28% increase in the risk of developing breast cancer in nurses who worked the night shift for over 15 years.

Psychosocial effects

The psychosocial effects that may result from frequent or sustained night-shift work aren't obvious or well studied. However, Estryn-Béhar et al. studied a cohort of over 25,000 nurses in Europe to examine the effects of nurses' shifts and the perceived impact on work and family life.4 Perhaps not surprisingly, the nurses who worked an 8- or a 12-hour shift during the day reported more satisfaction with both work and family life. Nurses who worked 8-, 10-, or 12-hour shifts during the evening and night reported a higher incidence of difficulties with managing work and family life. Because most nurses in this study were female (88.5%) and between ages 18 and 45 (76.7%), child-care provision emerged as a common dissatisfier.

Working night shifts has been associated with an increase in anxiety and depression.12 The research involved ICU nurses in Norway and their self-perception of anxiety and depression as measured by the Hospital Anxiety and Depression Scale. Findings revealed that 21.5% of critical care nurses who worked the night shift scored above the baseline for anxiety and depression, compared with 14.8% of all critical care nurses. Scores for both of these groups were significantly greater than the scores for the general population of Norway.

This study also reports that only 9% of the nurses in the research cohort reported getting adequate sleep before the shift start. Similarly, a Brazilian study of rotating shift workers showed that only 20% of men and 10% of women studied reported getting adequate sleep before starting their shifts.13

Fighting nature

Physiologic signs and symptoms associated with night-shift work may have their origins in the frequent disruption or desynchronization of a person's circadian rhythm.3,11 Nurses who work the night shift are challenging a biologically driven circadian rhythm that's compelling them to sleep when it's imperative for them to be awake, and vice versa. Night-shift nurses must resist the natural inclination to sleep at night. These nurses need to not only remain awake, but to maintain a high level of vigilance to provide quality patient care. Resisting the natural inclination to sleep can lead to issues with the ability to sleep at all.

Insomnia may be the most common complaint of night-shift nurses.12 The reasons include shifting schedules, working alternate shifts, rotating shifts, and difficulty sleeping in the daytime. Even getting a full 8 hours of sleep each day doesn't fully compensate for the circadian misalignment.14

Because most night nurses use different or combined strategies to manage the demands of family and work, a one-size-fits-all sleep strategy isn't likely to help night nurses manage their circadian challenges. (See Patterns of sleep: What's your strategy?)

Strategies to lessen ill effects

  • Maintain a cool and dark sleeping environment. The ideal room temperature for sleeping is between 60® F and 68® F (16® C to 20® C). As the ambient temperature approaches 75® F (24® C), the body has difficulty cooling itself, impairing sleep onset.15 Use window coverings to limit the amount of light entering the sleeping room.
  • Use a fan or device that emits “white noise” to help block out the normal sounds of day-to-day activities such as lawn mowers and traffic. Switch telephones to silent mode, when possible, to help ensure a quiet sleeping environment.
  • Use over-the-counter (OTC) and prescription sleep aids with caution. Keep in mind that adverse reactions are common, and the long-term use of certain drugs, such as sedative-hypnotics, can foster physical and/or psychological dependence. In addition, OTC medications, while generally accepted by the FDA as safe, can cause problems if used too frequently. Research has shown that consumption of melatonin, a popular sleep aid, may help someone fall asleep faster, but little evidence supports claims that it promotes longer or high-quality sleep.16
  • Encourage your hospital to allow night-shift workers to take breaks for short naps or rigorous exercise, such as climbing a flight of stairs or taking a brisk walk. A 10- to 15-minute nap in a break room or sleep room can provide a recharge and improve awareness and patient safety. Most current nursing research indicates that a brief nap may not only allay the effects of sleep deprivation, but it may also reduce the number of errors.17,18
  • Avoid leaving tedious or repetitive tasks until the end of the shift when fatigue or diminished awareness is more likely.
  • Use caffeinated drinks only early in the shift during the night work cycle.19
  • Wear dark glasses while returning home from a night shift to simulate the natural ending of a work shift toward the evening hours and help move into a more natural sleep cycle in spite of sleep initiation occurring in the morning or daylight hours.20 Masking the bright light of morning may also help prevent the natural circadian phase of waking up. Even small amounts of light may be enough to degrade the bioavailability of melatonin, which makes falling and remaining asleep more difficult.21,22
  • If your hospital cafeteria doesn't remain open with healthy options for the night shift, lobby to make refrigerated storage and healthy-choice vending machines available.
  • Get regular physical checkups and visit hospital-sponsored clinics to help identify potential problems. Ask your hospital to offer night-shift nurses free health screenings and vaccinations at later hours so you don't have to interrupt your sleep time.
  • If a coworker is having difficulty remaining alert, offer that nurse a respite by taking over his or her patients temporarily.

Heeding the alarm for safety

Hospitals have a duty to provide safe quality care around the clock. This goal requires skilled nurses working to the full extent of their abilities on all shifts. Nurses shouldn't hesitate to protect themselves and their colleagues by using strategies to lessen the effects of sleep disruption or fatigue and promote a culture of safety and security for both nurses and patients.

Patterns of sleep: What's your strategy?

Researchers from Vanderbilt University identified five main sleep strategies for shift workers and analyzed the usual sleeping patterns of 388 hospital-based night-shift nurses. They found that most nurses adapt with a combination of strategies, depending on their needs at the time. These strategies overlap in the study because of the inherent variability in sleep patterns and the difficulty of capturing discrete data.23

A more recent study examined various strategies with the objective of finding the most effective and least physiologically disruptive method of sleep management. This research found that the incomplete switcher and switch sleeper described below experienced less chronotype disturbance and possibly fewer cardiac problems.24

  • In the night stay strategy, nurses simply adapt all aspects of their life to the night shift. This was the rarest of strategies adopted (<3% of the nurses in the study). The authors felt that only those who reside in a large metropolitan area, with many 24-hour services, could adopt this strategy permanently.
  • The most common strategy was the no sleep strategy: On the day of the first night shift after time off, nurses arise at their usual morning time, stay awake for the entire day, and then work a 12-hour shift without sleeping beforehand. Because this involves staying up for more than 24 hours, this strategy may have a negative impact on patient-care delivery. Studies have shown that after as little as 17 hours of no sleep, cognitive abilities function at the level of someone with a blood alcohol level of 0.05%, which is the legal level for intoxication in most states.25
  • Other strategies included the nap proxy, which involves a 1- to 2-hour nap before the start of the night shift, the switch sleeper, where nurses on days off wake and sleep at the usual nonworking hours, and incomplete switcher, in which nurses tend to sleep late even on days off work.


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