Effects Of Night Shift Work Research Articles

Genome-wide methylation changes in night working women in Denmark: same altered promoter methylation of CLOCK and CRY2 as in breast cancer cases

ObjectivesA substantial body of literature has recently linked circadian disruption to breast cancer risk. Epigenetic association analysis also demonstrates differential promoter methylation in the core circadian genes in breast cancer...

Melatonin Treatment of Pediatric Residents for Adaptation to Night Shift Work

Night float rotations are used in residency training programs to reduce residents' sleep deprivation. Night shift work, however, is accompanied by deleterious effects on sleep, mood, and attention. To test whether melatonin reduces the deleterious effects of night shift work on sleep, mood, and attention in pediatric residents during night float rotation. Double-blind, randomized, placebo-controlled crossover. Participants took melatonin (3 mg) or a placebo before bedtime in the morning after night shift; completed a sleep diary and an adverse-effects questionnaire daily; and completed the Profile of Mood States and the Conners Continuous Performance Test 3 times in each study week to test mood and attention, respectively. A university-affiliated, tertiary-care pediatric hospital. Healthy second-year pediatric residents working 2 night float rotations. Standardized measures of sleep, mood, and attention. Twenty-eight residents completed both treatments; 17 completed 1 treatment (10 placebo, 7 melatonin). There was not a statistically significant difference in measures of sleep, mood, and 5 of 6 measures of attention during melatonin and placebo treatment. One measure of attention, the number of omission errors, was significantly lower on melatonin (3.0 +/- 9.6) than on placebo (4.5 +/- 17.5) (z = -2.12, P = .03). The isolated finding of improvement of 1 single measure of attention in a test situation during melatonin treatment was not sufficiently robust to demonstrate a beneficial effect of melatonin in the dose used. Other strategies need to be considered to help residents in adaptation to night shift work.

Night-shift work and risk of colorectal cancer in the nurses' health study.

Exposure to light at night suppresses the physiologic production of melatonin, a hormone that has antiproliferative effects on intestinal cancers. Although observational studies have associated night-shift work with an increased risk of breast cancer, the effect of night-shift work on the risk of other cancers is not known. We prospectively examined the relationship between working rotating night shifts and the risk of colorectal cancers among female participants in the Nurses' Health Study. We documented 602 incident cases of colorectal cancer among 78 586 women who were followed up from 1988 through 1998. Compared with women who never worked rotating night shifts, women who worked 1-14 years or 15 years or more on rotating night shifts had multivariate relative risks of colorectal cancer of 1.00 (95% confidence interval [CI] = 0.84 to 1.19) and 1.35 (95% CI = 1.03 to 1.77), respectively (P(trend) =.04). These data suggest that working a rotating night shift at least three nights per month for 15 or more years may increase the risk of colorectal cancer in women.

Night shift work

The deleterious effects of night shift work are discussed in relation to emergency physicians. Much of the early research is drawn from heavy industry sources and must be extrapolated to medical work. Disruption of circadian rhythms and Zeitgebers, caused by adherence to contemporary social schedules, causes recurrent difficulty for physicians who constantly change schedules. Adjustments in both physical surroundings and social structure that can make the effects of traumatic schedule change more tolerable are discussed.

Are there permanent effects of night shift work on sleep?

The sleep structures, patterns and subjective evaluations of 50–60 year old nurses with varying amounts of night shift experience during their nursing careers were compared with the sleep of 50–60 year old females without night shift experience. Seven nurses had extensive prior night shift experience and were currently on night shift schedules, seven nurses had extensive night shift experience but were on current day schedules, five nurses, currently on day schedules, had had limited night shift experience. There were limited differences between the nurses on current day schedules and the non shift women. The current night shift scheduled nurses showed characteristic displaced sleep responses. It was concluded that there is little support for an hypothesis of a permanent effect of night shift work experience on subsequent sleep.