The effects of frequently rotating shiftwork on sleep and the family life of hospital nurses

The effects of three frequently rotating shifts in an irregular sequence on the daily activities of 239 Japanese female hospital nurses were studied by the time-budget method. The nurses recorded their daily activities for several consecutive days. The questionnaire was returned by 80.8% of the participants, and recordings of 1016 days were analysed. A two-way analysis of variance clarified that the shift combination influenced the daily activities. The most distinct result was that nurses spent significantly more time on free-time activities on the day when they worked the night shift followed by the evening shift than they did on the day when they worked any other shift combination. Nurses offset sleep deprivation either by sleeping during the day before and after working the night shift (82-100%) or by sleeping 2 to 4 h later in the morning after working the evening shift and on days off. There was a strong positive correlation between total sleep time (including day sleep) and the length of the interval between two consecutive shifts (r = 0.95, p < 0.001). This result suggests that more than 16 h between work shifts is required to allow more than 7 h of total sleep time. In an analysis by household status, nurses who had young children (average age, 2.8 years) slept less and spent less time on free-time activities than did other nurses.     

Adaptation and readaptation to different shift work schedules measured with sleep diary and actigraphy.

In this study we examine sleep during adaptation and readaptation to different shift work schedules in the offshore oil industry. The sleep of 19 offshore workers was assessed daily for 1 week before, during the work period, and for 1 week after 3 different work schedules: (1) day (14 consecutive days of work), (2) night (14 consecutive nights of work), and (3) swing shift work (first 7 nights with night work then 7 days of day work). The workers' sleep was assessed for 84 days. Actigraphy and sleep diary estimates of sleep was applied assessing: (1) adaptation to offshore shift work, (2) sleep across the 2 offshore work weeks, and (3) readaptation after the work period. Regarding adaptation, sleep efficiency was higher when working day than night and swing shift the first week of work. Sleep quality was better during swing than regular day/night shifts the first week of work. Total sleep time was longer during day and night shift than swing shift across the 2 work weeks. Sleep efficiency, based on sleep diaries, was higher during day than night and swing shift during the 2 work weeks. There were no significant differences between the shifts in readaptation in terms of sleep. To conclude, adaptation to swing shift was more difficult than adaptation to regular day and night shifts in terms of sleep. Readaptation to day work after 1 week of night work affected sleep negatively. There were no differences between the shift schedules the week after the work period. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Differential roles of neuroticism, extraversion, and event desirability for mood in daily life: An integrative model of top-down and bottom-up influences.

Top-down and bottom-up approaches were combined to assess the relative impact of extraversion, neuroticism, and daily events on daily mood. Ninety-six community-residing men completed diaries for 8 consecutive nights. Extraversion predicted positive mood, whereas neuroticism predicted positive and negative mood. Undesirable events predicted negative mood and, more modestly, positive mood. Desirable events predicted positive mood. Negative dispositional and situational factors play a larger role in daily positive affect than positive factors do in daily negative affect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The BRCA1 and BRCA2 breast cancer genes

This review discusses the need for sleep, effects of sleep deprivation on behaviour and performance in the military, and sleep management recommendations to optimise combat effectiveness. Most people, regardless of sex or race, prefer 7 to 8 hours of sleep each night. Sleeping during the day is less recuperative. Continuous sleep is more effective than multiple short naps-even when the total hours for naps is more. Ten to 20 minute naps are useful when continuous sleep is not possible. Sleep inertia is the 5 to 30 minute period of sluggishness after awakening and important military tasks should be avoided. Previously, continuous work episodes (CWEs) duration was restricted by limited night vision, unreliable equipment and reduced endurance of military personnel. With improved technology, CWEs are now restricted primarily by endurance which is affected by sleep deprivation. This was one of the experiences noted in recent conflicts (e.g. Desert Storm) by personnel in the air force, army and navy. Since there will be changes in operational requirements, several work-rest-sleep plans must be prepared. Sleeping the preferred 7 to 8 hours per 24 hours the week before an operation may help prepare for optimal performance. Personnel should be familiarised with conditions under which they may sleep. During combat, sleep management should ideally avoid situations where all personnel are exhausted at the same time. As sleep debt accumulates, a person's mood, motivation, attention, alertness, short-term memory, ability to complete routines, task performance (errors of omission more than errors of commission) and physical performance will become more negatively affected. Counter measures must then be taken (e.g. time for sleep or naps, changing routines or rotating jobs). Drugs like caffeine and amphetamine can help personnel stay awake. However, they may also keep them awake when they need to sleep- and on awakening, they could suffer from "hang-overs" and are less efficient. Sleep lost need not be replaced hour-for-hour. Therefore, after operations, personnel need continuous sleep for only 10 to 12 hours as longer sleep increases sleep inertia and delays getting back to normal schedules.     

Comparative study to determine the optimal melatonin dosage form for the alleviation of jet lag

To compare the impact of various dosage forms of melatonin and placebo on jet lag symptoms, 320 volunteers who had flights over 6 to 8 time zones were recruited for a double-blind, randomized, placebo-controlled study. The volunteers received either melatonin 0.5-mg fast-release (FR) formulation, melatonin 5-mg FR formulation, melatonin 2-mg controlled-release (CR) formulation, or placebo. The study medication was taken once daily at bedtime during 4 days after an eastward flight. The volunteers completed the Profile of Mood States (POMS), sleep log, and symptoms questionnaires once daily and the Karolinska Sleepiness Scale (KSS) three times daily prior to departure and during the 4 days of medication intake postflight. A total of 234 (73.1%) participants were compliant and completed the study. The FR melatonin formulations were more effective than the slow-release formulation. The 5-mg FR formulation significantly improved the self-rated sleep quality (p < .05), shortened sleep latency (p < .05), and reduced fatigue and daytime sleepiness (p < .05) after intercontinental flight. The lower physiological dose of 0.5 mg was almost as effective as the pharmacological dose of 5.0 mg. Only the hypnotic properties of melatonin, sleep quality and sleep latency, were significantly greater with the 5.0-mg dose.     

Exercise and the experience and appraisal of daily stressors: a naturalistic study

Thirty-eight men and 35 women completed diaries of exercise, mood, and the experience and appraisal of daily stressors over 12 consecutive days. It was hypothesized that exercise would be associated with positive moods and with the experience of fewer daily stressors. Positive moods were rated higher and depression lower on exercise days than no-exercise days. Participants low in trait anxiety reported fewer stressful events on the days on which they exercised. Those with strong personal (health, physical appearance, and mood) motives for exercise reported more stressful daily events overall; in addition, they experienced more potentially stressful events as nonstressful on the days during which they engaged in physical exercise. The results are discussed in relation to the acute after-effects of exercise on mood and stress responsivity and the long term of psychological benefits of regular exercise.     

Age, smoking, and negative affectivity as predictors of sleep patterns among shiftworkers in two environments.

Although adaptation to shiftwork has been widely studied, little is known about how individual and environmental factors combine to influence sleep among shiftworkers. This study examined age, smoking, and negative affectivity (NA) as predictors of sleep duration and quality for 3 work phases (day shifts, DS; night shifts, NS; and leave periods, LP). Data were collected from personnel working 12-hr shifts, onshore (n = 330) or offshore (n = 456). Individual factors predicted patterns of sleep measures across the DS, NS, and LP phases onshore, but not offshore; onshore, work phase interacted with smoking and with age to predict sleep duration and with NA to predict sleep quality. The role of the offshore environment in shiftwork adaptation is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The therapeutic focus in significant sessions of master therapists: a comparison of cognitive-behavioral and psychodynamic-interpersonal interventions

This study was designed to test the hypothesis that bright light (BL) can have a stimulating effect on vigilance even in the absence of suppression of melatonin secretion and that this effect can be detected when measured in subjects with low vigilance levels. Seven normal subjects were exposed to bright-white light (BL group) and seven to dim-red light (DL group) on 2 consecutive days, each following a night of 4-h sleep restriction. The light treatment was administered in the late morning, between 0900 and 1330 hours. Salivary melatonin measurements indicated that BL did not suppress melatonin secretion or induce circadian phase shifts. The effects of the two treatments were compared on validated measures of daytime vigilance: immediate effects were evaluated on subjective alertness during the light treatment, whereas short-term (0.5-10.5 h) and long-term (20.5-34.5 h) carryover effects were measured on subjective alertness, daytime sleep latencies (DSL), and psychomotor performance. After two nights of sleep restriction, subjective alertness and daytime sleep latencies decreased significantly, but there was no effect of the light treatment. BL treatment did not affect global performance, but there was an effect on the strategy used by the subjects, as shown by faster reaction times and increased percentage of errors in the BL group. It was concluded that daytime BL exposure did not have a stimulating effect on our measures of vigilance even in sleep-deprived subjects but that it may increase physiological arousal and affect the subjects' behavior in some specific performance tasks.     

Zolpidem-Related Effects on Performance and Mood During Simulated Night-Shift Work.

The effects of zolpidem, a nonbenzodiazepine hypnotic, on psychomotor task performance, subjective effects, and food intake were examined during simulated shift work. Seven participants completed this 23-day, within-participant design, residential laboratory study. They received a single oral zolpidem dose (0, 5, or 10 mg) 1 hr before bedtime for 3 consecutive days under 2 shift conditions: day shift and night shift. When participants received placebo, next-day performance and subjective effects were disrupted, and food intake was decreased during the night shift. Zolpidem improved subjective reports of sleep quality and, to a lesser extent, next-day performance. Next-day mood, however, was worsened by zolpidem. Food intake was unaffected by zolpidem. These data indicate that shift changes produce performance impairments, mood alterations, and decreases in food intake, and that zolpidem attenuates some shift-change-related disruptions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Immunological requirements for a subunit vaccine against tuberculosis

Although the causes are different, totally blind people (without light perception) and night shift workers have in common recurrent bouts of insomnia and wake-time sleepiness that occur when their preferred (or mandated) sleep and wake times are out of synchrony with their endogenous circadian rhythms. In this article, the patterns of circadian desynchrony in these two populations are briefly reviewed with special emphasis on longitudinal studies in individual subjects that used the timing of melatonin secretion as a circadian marker. In totally blind people, the most commonly observed pattern is a free-running rhythm with a stable non-24-h circadian period (24.2-24.5 h), although some subjectively blind people are normally entrained, perhaps by residually intact retinoypothalamic photic pathways. Experiments at the cellular and behavioral levels have shown that melatonin can produce time dependent circadian phase shifts. With this in mind, melatonin has been administered to blind people in an attempt to entrain abnormal circadian rhythms, and substantial phase shifts have been accomplished; however, it remains to be demonstrated unequivocally that normal long-term entrainment can be produced. In untreated night shift workers, the degree and direction of phase shifting in response to an inverted sleep-wake schedule appears to be quite variable. When given at the optimal circadian time, melatonin treatment appears to facilitate phase shifting in the desired direction. Melatonin given prior to a night worker's daytime sleep also may attenuate interference from the circadian alerting process. Because melatonin has both phase-shifting and sleep-promoting actions, night shift workers, who number in the millions, may be the most likely group to benefit from treatment.     

Daily occupational stressors and marital behavior.

This study examined daily fluctuations in marital behavior (anger and withdrawal) as a function of same-day job stressors, using hierarchical linear modeling (HLM). Forty-three couples provided daily diary reports of their workload and negative social interactions at work on 5 consecutive days. Within-subject analyses demonstrate that husbands and wives reported greater marital anger and withdrawal following negative social interactions at work, and wives reported greater marital anger and withdrawal following days of heavy workload. Mediation analyses provide support for the negative mood spillover hypothesis (e.g., workload no longer predicted wives' marital anger when controlling for negative mood). Between-subjects analyses suggest that spouses in high-conflict families may be especially vulnerable to the effects of job stressors on marital interaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of melatonin on aqueous humor flow in humans during the day

BACKGROUND: Aqueous humor flow through the anterior chamber of the eye undergoes a circadian cycle. The rate of flow during the day is twice as high as the rate of flow at night. The pineal hormone, melatonin, also undergoes a circadian cycle. Melatonin levels are high at night, whereas aqueous humor flow is low. The authors studied the effect of oral melatonin on aqueous humor flow in humans. METHODS: The effect of melatonin on aqueous humor flow was evaluated in 19 healthy human volunteers in a randomized, masked crossover study with a placebo control. The hormone or placebo was administered orally during the day when endogenous levels of melatonin are low. Aqueous flow was measured by fluorophotometry for 8 hours. RESULTS: The mean rate of flow during melatonin treatment was 2.71 +/- 0.64 microliters/minute (+/- standard deviation). The rate of flow during placebo treatment was 2.80 +/- 0.66 microliters/minute. There is no statistically significant difference between these two rates (P = 0.4). With a sample size of 19, the study has a power of 92% to detect at least a 15% difference in the rate of flow under the two conditions. Measurement of plasma concentration of melatonin in five subjects confirmed that concentrations after oral dosage reached peaks comparable with the normal endogenous nocturnal peaks. CONCLUSIONS: The authors conclude that melatonin concentrations during the day, comparable with plasma concentrations that occur spontaneously during sleep, do not suppress aqueous humor formation. The authors find no support for the idea that plasma melatonin, per se, can suppress aqueous formation or that the circadian rhythm of plasma melatonin is primarily responsible for the circadian rhythm of aqueous humor flow.     

Fibromyalgia: The role of sleep in affect and in negative event reactivity and recovery.

Objective: Fibromyalgia (FM) syndrome is a chronic pain condition characterized by diffuse muscle pain, increased negative mood, and sleep disturbance. Until recently, sleep disturbance in persons with FM has been modeled as the result of the disease process or its associated pain. The current study examined sleep disturbance (i.e., sleep duration and sleep quality) as a predictor of daily affect, stress reactivity, and stress recovery. Design and Measures: A hybrid of daily diary and ecological momentary assessment methodology was used to evaluate the psychosocial functioning of 89 women with FM. Participants recorded numeric ratings of pain, fatigue, and positive and negative affect 3 times throughout the day for 30 consecutive days. At the end of each day, participants completed daily diary records of positive and negative life events. In addition, participants reported on their sleep duration and sleep quality each morning. Results: After accounting for the effects of positive events, negative events, and pain on daily affect scores, it was found that sleep duration and quality were prospectively related to affect and fatigue. Furthermore, the effects of inadequate sleep on negative affect were cumulative. In addition, an inadequate amount of sleep prevented affective recovery from days with a high number of negative events. Conclusions: These results lend support to the hypothesis that sleep is a component of allostatic load and has an upstream role in daily functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relationships between nocturnal activity, parental ratings of daytime activity and measues from the Children's Sleep Behaviour Scale.

Monitored the nocturnal activity levels of 20 boys and 20 girls (mean age 10.46 yrs) from 12:00 AM to 6:00 AM over 2 consecutive nights in their homes. Frequency of sleep-related behaviors based on retrospective parental ratings was assessed by the Children's Sleep Behavior Scale (CSBS). Children who were rated high on sleep behaviors with an observable motor component were also more active during the night, thereby validating the motor subscale of the CSBS. Nocturnal activity was associated with another CSBS-derived sleep score that included items with positive affective content, such as laughing and smiling while asleep. Children who showed bedtime resistance behaviors and complained of difficulty going to sleep were not more active during the night. Gender, age, and parental perception of daytime activity levels were not related to objective measures of nocturnal activity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of one night's sleep deprivation on temperature, mood, and physical performance in subjects with different amounts of habitual physical activity

Eleven healthy males were studied twice. On one occasion (control, C), they slept (night 1) and then underwent a battery of tests at 4 h intervals from 06:00 day 1 to 02:00 day 2; then, after a normal sleep (night 2), they were tested from 10:00 to 22:00 on day 2. On the second occasion (sleep deprivation, SD), the subjects remained awake during night 1. Each battery of tests consisted of measurements of tympanic membrane temperature, profile of mood states (POMS), muscle strength, self-chosen work rate (SCWR), perceived exertion, and heart rate (HR) while exercising on a stationary cycle ergometer. Subjects also kept a diary of their activities during the two days and answered a questionnaire about their habitual physical activity. Results showed a significant negative effect of sleep deprivation on most mood states on day 1, but no effect on the other variables. By day 2, mood had tended to recover, though muscle strength tended to be worse in both control and sleep-deprivation experiments. There was also a more general tendency for negative effects to be present at the end of day 1 (02:00) or at the beginning of day 2 (10:00). There was limited support for the view that subjects who were habitually more active showed less negative effects after sleep deprivation and responded less adversely to the poor sleep achieved on the university premises (night 2). These results stress the considerable interindividual variation in the responses to sleep loss and, therefore, the difficulty associated with giving general advice to individuals about work or training capability after sleep loss.     

Pain inhibition, nicotine, and gender.

The ability of nicotine to decrease sensitivity to pain in humans has been a subject of dispute. Decreased sensitivity has been demonstrated in studies involving men, whereas the effect has been less obvious or absent in studies involving predominantly, or entirely, women. To determine whether there are gender differences in nicotine's hypoalgesic actions, ratings of electrocutaneous stimulation were obtained from 30 male and 44 female smokers and nonsmokers under placebo and nicotine conditions. Nicotine increased the pain threshold and tolerance ratings of men but had no effect on the pain ratings of women. Among men, there was no effect of smoking history, suggesting that the changes in pain perception reflect a direct pain-inhibitory effect of nicotine rather than a relief from acute nicotine withdrawal. Nicotine had no effect on mood or task ratings, indicating that the antinociceptive effects observed were not due to nicotine's putative mood effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Targeted Naltrexone Treatment Moderates the Relations Between Mood and Drinking Behavior Among Problem Drinkers.

One hundred fifty-three problem drinkers were randomly assigned to receive naltrexone 50 mg or placebo on a daily or targeted (to high-risk drinking situations) basis. Using structured nightly diaries, participants recorded negative and positive mood, desire to drink, and alcohol consumption over 8 weeks. Results indicated that individuals engaged in any drinking and heavy drinking more on days characterized by relatively higher levels of positive or negative mood states. Naltrexone attenuated the positive association between heavy drinking and both positive and negative mood, and targeted administration attenuated the positive association between heavy drinking and positive mood. There was also evidence that desire to drink mediated the effect of targeted administration on the relation between positive mood and any drinking that day. These findings underscore the utility of daily measurement for understanding the processes that underlie pharmacological interventions for problem drinking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of temazepam on oxygen saturation and sleep quality at high altitude: randomised placebo controlled crossover trial

OBJECTIVE: To determine the effects of temazepam on the quality of sleep and on oxygen saturation during sleep in subjects at high altitude. DESIGN: Randomised, blinded, crossover, placebo controlled trial. SETTING: Base camp at Mount Everest (altitude 5300 m). SUBJECTS: 11 members of British Mount Everest Medical Expedition recently arrived at base camp. INTERVENTION: Participants were randomly allocated to receive either temazepam 10 mg or placebo on their first night at base camp and the other treatment on the second night. MAIN OUTCOME MEASURES: Quality of sleep (assessed subjectively), mean arterial oxygen saturation value, and changes in saturation values (as measure of periodic breathing) while participants taking temazepam or placebo. RESULTS: All participants noted subjective improvements in sleep. Mean saturation value remained unchanged when temazepam was compared with placebo (74.65% v 75.70%, P = 0.5437). There were fewer changes in oxygen saturation when participants took temazepam and when measured as decreases > 4% below the mean value of saturation each hour (P = 0.0036, paired Student's t test (two tailed)). CONCLUSIONS: Participants taking temazepam at 5300 m showed no significant drop in mean oxygen saturation values during sleep. Both the number and severity of changes in saturation during sleep decreased and the quality of sleep improved. This may be a result of a reduction in the number of awakenings and might lead to greater respiratory stability and fewer episodes of periodic breathing. This has the effect of improving the quality of sleep and reducing the number of periods of desaturation during sleep.     

The effect of mood on sleep onset latency and REM sleep in interepisode bipolar disorder.

The present study investigates whether interepisode mood regulation impairment contributes to disturbances in sleep onset latency (SOL) and rapid eye movement (REM) sleep. Individuals with interepisode bipolar disorder (n = 28) and healthy controls (n = 28) slept in the laboratory for 2 baseline nights, a happy mood induction night, and a sad mood induction night. There was a significant interaction whereby on the happy mood induction night the bipolar group exhibited significantly longer SOL than did the control group, while there was no difference on the baseline nights. In addition, control participants exhibited shorter SOL on the happy mood induction night compared to the baseline nights, a finding that was not observed in the bipolar group. On the sad mood induction night, participants in both groups had shorter SOL and increased REM density when compared to the baseline nights. Bipolar participants exhibited heightened REM density compared to control participants on both nights. These results raise the possibility that regulation of positive stimuli may be a contributor to difficulties with SOL, while hyperactivity may be characteristic of REM sleep. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ketoconazole and other imidazole derivatives are potent inhibitors of peroxisomal phytanic acid alpha-oxidation

Twelve young adults were treated with either melatonin, 3 mg or 6 mg, or placebo, at two different times before an early evening nap (18.00-20.00 h) according to a balanced double-blind Latin square design. Polysomnographic monitoring revealed that both dosages of melatonin significantly shortened sleep latency and increased total sleep time in comparison to placebo, irrespective of the time of administration. Subjects also tended to assess their sleep as 'deeper' after melatonin treatment. Based on previous data and the present results, it was concluded that exogenous melatonin exerts hypnotic effects only when circulating levels of endogenous melatonin are low.