Self-Reported Sleep Disturbances in Employed Women

Transcription

1 " Sleep. 15(6): American Sleep Disorders Association and Sleep Research Society Self-Reported Sleep Disturbances in Employed Women Kathryn A. Lee Department 0/ Family Health Care Nursing. University o/california, San Francisco. U.S.A. Summary: To explore the incidence and types of sleep disturbances in employed women, 760 registered nurses completed a health survey that included questions about their sleep patterns and sleep quality. Comparisons are made between those nurses working permanent day, permanent evening, permanent night, and rotating shifts. As expe~ted, t?ere were higher incidences of sleep disturbances and excessive sleepiness for women working night and rotatmg ShftS, but age and family factors, rather than caffeine and alcohol intake, contributed to the differences in types of sleep disturbances these women experienced. Key Words: Women's sleep-employment-night shift Sleep disturbance-sleep deprivation. Although women now constitute over 50% of the U.S. workforce (1), the majority still maintain traditional family roles, with primary responsibility for child care and household tasks. Thus, they typically have a "double work day" or a "second shift" (2-4). Data on the quantity and quality of sleep in employed men are readily available, but there are very little data on women, particularly in the United States. Because of the double work day for most women, generalizing from studies of sleep disturbances in employed men to disturbances in employed women is problematic. n large community-based studies of working and nonworking individuals, sleep disturbances and use of medications were found to be more prevalent for older women (5,6). Fatigue, often a symptom of disturbed sleep, is also more prevalent among women compared to men (7-9). Working women, regardless of age, are reported to be more-frequent users of sleeping pills and tranquilizers than working men (10). The few studies that have been conducted on employed women have primarily been outside the United States or restricted to a particular age group, shiftwork schedule, or type of sleep disturbance (10-14). The incidence and types of sleep pattern disturbance among working women in the United States remain unknown. The purpose of this study was to describe the incidence of sleep pattern disturbances in a sample of professional women and contrast those disturbances among women working a variety of shift schedules. Accepted for publication July Address correspondence and reprint requests to Dr. Kathryn A. Lee, N411 Y, Box 0606, School of Nursing, University of California, San Francisco, California , U.S.A. 493 METHODS Data were gathered with an investigator-developed questionnaire containing primarily forced-choice answers to questions about work, family, health, and sleep. These questionnaires were distributed to female registered nurses working at least 4 days/week and 32 hours/week in seven hospitals on the west coast of the United States. Participants completed the questionnaires on their own time and returned them in postagepaid envelopes. A $2.00 payment was attached to the questionnaire. The response rate was 69%. ncluded in the questionnaire packet was the morningness--eveningness scale, modified for this study of shiftworking nurses (15), and five-point Likert-type scales for job and shift schedule satisfaction. As part of a dietary assessment, participants were also asked to indicate the number of servings of caffeine and alcohol consumed on an average day in the past week. They were asked to indicate the clock times for sleep onset and awakening on work days and days off. Questions pertaining to sleep disturbances were modified from a section of the Stanford Sleep Questionnaire and Assessment of Wakefulness (SQAW) (16), and included a general sleep disturbance scale (GSDS) as well as specific items related to initiating sleep, mid sleep awakenings, arousing from a sleep period, and maintaining wakefulness. While retaining the content ofthe questions, respondents were asked to think about the past month rather than the past 6 months, and respond on 1 O-point scales from 0 ("never") to 9 ("all the time") rather than on five-point scales or yes/no scales. The GSDS consists of 21 items related to frequency in the past month of difficulty getting to sleep (one

2 494 K A. LEE TABLE 1. Demographic characteristics of the sample by shift expressed as means ± SD Day Characteristic (n = 316) Age (years)a 40.6 ± 9.9 Children 0.7 ± 1.0 Employed (years)" 17.1 ± 9.8 Work/week (hours) 38.2 ± 3.7 Schedule satisfaction a 2.1 ± 1.0 Sleep: work days (hours)a 7.5 ± 0.9 Sleep: days off (hours) 8.8 ± 1.2 Naps (number/week)a 1.4 ± 2.8 Chronotype mean score a 57.4 ± 9.7 Caffeine (servings/day) 4.9 ± 4.0 Alcohol (servings/day) 1.4 ± 2.5 adf= 3,752;F~ 17.2,p < Evening Night Rotating (n = 194) (n = 178) (n = 71) 36.2 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 2.9 item), waking up during sleep (one item), waking up too early from sleep (one item), quality of sleep (three items: sleeping poorly, not feeling rested upon awakening, and not feeling satisfied with sleep), quantity of sleep (two items: too little sleep and too much sleep), fatigue and alertness at work (seven items), and use of substances to help induce sleep (six items, ranging from aspirin to prescription drugs). To ascertain specific reasons for responses on the GSDS, the questionnaire contained 10 items on aspects of sleep hygiene and frequency of sensations experi. enced as sleep onset occurs, 27 items on the frequency of specific reasons for midsleep awakenings, eight items relevant to problems and sensations experienced when arousing from sleep at the final awakening, and 19 items on situations in which they struggled to maintain wakefulness. ANALYSES The incidences of specific sleep disturbances were determined by calculating the percentages of occurrence according to shift schedule as: not present (mean of scores within each dimension :::; 1), rare (mean > 1 :::; 2), occasional (mean > 2 :::; 3) and frequent (mean >3). The mean differences between nurses working four types of shifts were compared using the ANOV A program available in SPSSX. Because sleep is affected by age (17) and because rotating nurses were significantlly younger than the women in the other three groups, age was entered as a covariate for tests of differences in mean scores on these seven dimensions of disturbed sleep. To account for the multiple comparisons, a Bonferroni correction factor was used. For 20 comparisons at alpha = 0.05 ( ), the criteria for significance was set at p :::; Post-hoc t tests were used to indicate where significant differences occurred betwee:n the four groups. RESULTS Descriptive characteristics of the sample The sample consisted of 316 women working permanent day shift ( hours), 195 working permanent evening shift ( hours), 178 working permanent night shift ( hours), and 71 working rotating shifts (weekly or monthly rotations to all three shifts, either clockwise or counter-clockwise). Compared to other studies (5,6), women in this study were slightly older. As seen in Table 1, the rotating nurses were younger and the permanent day nurses were older than those working permanent evenings or nights. Ages ranged from years in the group of rotating nurses and years in the other three groups. Age was predictive of the presence of children in the home (F 1,716 = 24.8, p < 0.001). After accounting for age, however, there was no significant difference by type of shift (p = 0.06). As a reflection of age, more women who worked permanent days (20%) or nights (23%) had children in the home compared to women who worked evenings (13%) or rotated (7%). Prior experience with night shift work was reported by 510 (68%) of the permanent day and evening nurses. As expected, age was significant (F 1,729 = 1,743.6, P < 0.001) in accounting for the difference in number of years working at the same job. The younger nurses and those who rotated shifts were less satisfied with their work schedule than permanent shift nurses (Table 1), with both age and shift accounting for the significant difference in schedule satisfaction (F 4,729 = 24.8, P < 0.001). U sing the morningness-eveningness scale (15), women were categorized as definite/moderate evening type (16-41 points), neither type (42-58 points), or definite/moderate morning type (59-86 points). The majority (51.3%) of permanent day workers were morning types and only 8% were evening types. The majorities of the other three shifts were neither morn-.~ 1

3 . SLEEP DSTURBANCES N EMPLOYED WOMEN 495 TABLE 2. Means (±SDJ, medians, and ranges for dimensions of sleep disturbance Day Sleep disturbance variable (n = 316) General sleep disturbance Mean 47.3 (13.8) scale (GSDS) Median 45 Range Substances to aid sleep Mean 0.5 (0.9) Median 0.2 Range Poor sleep quality Mean 4.5 (1.3) Median 4.6 Range Too little sleep Mean 4.4 (2.6) Median 4 Difficulty initiating sleep Mean 2.5 (2.3) Median 2 Midsleep awakenings Mean 4.7 (2.9) Median 4 Early awakenings Mean 3.1 (2.8) Median 2 Sleepiness Mean 2.3 (0.8) Median 2.1 Range Evening Night Rotating (n=194) (n = 178) (n = 71) 45.5 (13.1) 60.5 (16.3) 56.6 (18.4) (0.8) 0.7(1.0) 0.7(1.3) (1.2) 4.3 (1.2) 4.4 (0.9) (2.5) 6.0 (2.4) 5.3 (2.4) (2.2) 3.4 (2.5) 3.3 (2.4) (2.8) 5.8 (2.7) 5.2 (2.8) (2.6) 5.1 (2.6) 4.0 (2.6) (0.9) 3.4 (1.3) 3.0 (1.4) ing nor evening type. Age and shift were significant (F = 31.4, P < 0.001) in explaining chronotype (Table 1). Older women and those who worked permanent day shift were more likely to be morning types. As seen in Table 1, there was no significant difference between groups in self-reported caffeine consumption (including coffee, tea, or cola). Three or more servings of caffeine-containing beverages were consumed by 30% of the day nurses, 49% of the evening nurses, 46% of the night nurses, and 42% of the rotating nurses. For alcohol consumption there was a trend in the data (p = 0.08): more day (53%) and rotating (51 %) nurses consumed at least one serving of alcohol per day than nurses on permanent evenings (38%) or nights (35%). Neither the covariate of age nor the main effect of shift was significant in explaining caffeine or alcohol intake. General sleep disturbance Of the 760 women surveyed, 29% reported having current problems with sleep and 31 % reported having a sleep problem in the past. When asked if they ever had a "sleep problem that occurred in cycles," 1.2% (n = 15) described a premenstrual night of insomnia. The scores for the 21 items on the GSDS ranged from seven to 136. The means, medians, and ranges for each of the four groups are presented in Table 2 and the scale was internally consistent (Cronbach's alpha reliability coefficient = 0.88). Compared to nurses working other shifts, very few evening nurses complained of sleep disturbance (Table 3). Although age was a significant covariate, the main effect of shift was also significant (Table 4). Younger nurses on all shifts and those working permanent nights were more likely to experience disturbances in their sleep. Use of substances to aid sleep Six items within the GSDS related to the use of a variety of substances that may induce sleep. Although these items would not be expected to have internal consistency as a subscale, there was modest reliability (Cronbach's alpha = 0.62). n general, very little use was reported by any of the four groups. However, sleep aids were most often used by women working permanent nights and rotating shifts (Table 3), a finding similar to reports of male shiftworkers. As seen in Table 4, age was not significant, but the main effects of shift did reveal a trend (p = 0.01). Sleep quality The three items within the GSDS related to sleep quality constituted an internally consistent subscale (Cronbach's alpha = 0.79). Age was a significant covariate, with younger women having poorer sleep quality. Shift schedule had no significant effect (Table 4).

4 496 K. A. LEE TABLE 3. Percentages of self-reported sleep disturbances in employed women by type of shift Eve- Day ning Night Ro- (n = (n = (n = tating Sleep disturbance 316) 194) 178) (n = 71) General sleep disturbance Not present (~21) Rare (21-42) Occasional (43-63) Frequent (~64) Use substances to aid sleep Never (0-1.0) Rarely ( ) Occasionally ( ) Frequently ( ) Poor sleep quality Never (0-1.0) Rarely ( ) Occasionally ( ) Frequently ( ) Too little sleep Never (0-1.0) Rarely ( ) Occasionally ( ) Frequently ( ) Difficulty initiating sleep Never (0-1.0) Rarely ( ) Occasionally ( ) Frequently ( ) Midsleep awakenings Never (0-1.0) Rarely ( ) Occasionally ( ) Frequently ( ) Early awakenings Never (0-1.0) Rarely ( ) Occasionally ( ) Frequently ( ) Sleepiness Never (0-1.0) Rarely ( ) Occasionally ( ) Frequently ( ) Sleep quantity The GSDS contained two items related to amount of sleep. n an analysis of their self-reported ratings of too little sleep, the incidence was higher for permanent night nurses compared to permanent evening nurses (Tables 2 and 3). Although the permanent night nurses thought they received too little sleep, they had more calculated hours of sleep on work days and days off than nurses in the other three groups (Table 1). n addition to age, there was a main effect of shift (Table 4). The younger nurses working permanent nights and rotating shifts reported sleeping significantly less than TABLE 4. ANOVA tables for types of sleep disturbance by shift schedule, with age as a covariate Sleep disturbance variable General sleep disturbance Substances to aid sleep Poor sleep quality Too little sleep Naps Difficulty initiating sleep Midsleep awakenings Early awakenings Sleepiness a p < b P = Covariate Age (df= 1,752) F o o O.0 b Main effects Shift (df= 3,749) F b 14.0" a Explained (df= 4,748) F a the older women and those working permanent day or evening shifts. As indicated in Table 1, all groups of women had longer sleep periods on their days off than during their work days. Only five of the 178 permanent night workers maintained the same daytime sleep period during their days off. Age was not a significant covariate, but shift was significant for sleep period time and hours slept during the past week on work days and on days off (F 1,460 = 38.7, P < 0,001). The average number of naps/week is presented by group in Table 1. There was a significant difference in the number of naps taken by night and rotating workers compared to permanent day and permanent evening nurses, but the covariate of age was not significant (Table 4). Ofthe day shift nurses, 50% reported taking a nap for more than 5 minutes during the past week. The incidence was about the same for evening shift nurses (46%), but much higher for night shift (84%) and rotating shift nurses (73%). Difficulty initiating sleep Within the GSDS was an item asking respondents to indicate how often in the past month they had difficulty getting to sleep. The means, medians, and ranges for this item are presented in Table 2 according to the four shift schedules. As indicated in Table 3, fewer day and evening nurses had difficulty getting to sleep. The covariate of age was significant and there was a main effect due to shift, with older women on permanent day and evening shifts having less-frequent problems associated with sleep onset than permanent night and rotating shift workers (see Table 4). Midsleep awakenings As part of the GSDS, women were asked about the frequency with which they awakened during their sleep i j.. -,

5 SLEEP DSTURBANCES N EMPLOYED WOMEN 497 periods. The means, medians, and ranges for this item are presented in Table 2. Not unexpectedly, the incidence of difficulty maintaining sleep for the night and rotating nurses was higher compared to day and evening nurses (see Table 3). The covariate of age and the main effect of shift explained the differences in sleep maintenance (see Table 4). The younger women and those on permanent nights and rotating shifts had significantly more difficulty maintaining sleep. n response to 27 specific items related to midsleep interruptions, women who worked at night or rotated shifts reported awakenings due to noise (80.2%), hunger or thirst (47.6%), child care responsibilities (37%), night sweats (31.9%), and indigestion (21 %) as the five most prevalent reasons. When the data were re-analyzed by age group, it was women over 40 years of age (n = 280), regardless of the shift they worked, who experienced more disrupted sleep because of hot flashes (24%). t was women under 40 years of age (n = 480), regardless of the shift they worked, who experienced more awakenings during their sleep because of child care responsibilities (24%). Of those women over 40 years of age, 10% reported that they snored to such an extent that someone complained. n comparison, only 5% of women under 40 years of age reported that they snored loudly enough. for someone to complain. Early awakenings One item on the GSDS pertained to awakening too soon from the sleep period. The means, medians, and ranges for this item are reported for each of the four groups in Table 2. The covariate of age was not significant (p = 0.006), whereas shift had a significant effect (Table 4). Sleepiness Within the GSDS were seven items related to maintaining vigilance during work hours. This subsca1e was internally consistent (Cronbach's alpha = 0.82) and the means, medians, and ranges are presented in Table 2. The covariate of age and the main effect of shift were significant (Table 4). The younger workers and those working nights and rotating shifts reported more difficulty maintaining wakefulness than older women and those working day and evening shifts (see Table 3). None ofthe permanent day or evening nurses reported frequent sleepiness, whereas 4% of the permanent night nurses and 4.3% of the rotating nurses reported frequently feeling sleepy. As Akerstedt (18) stated in his review article on sleepiness as a consequence of shiftwork, how one asks about sleepiness will influence the prevalence reported by the investigator. n his survey of 1,000 train drivers who were asked how often they fell asleep during work, the prevalence was 11 %. When women in this sample were asked how often in the past month they struggled to stay awake while taking care of a patient, 19.3% of the night and rotating workers, compared to 3.8% of the day and evening workers, reported some degree of struggle. Of the entire sample, 170 women (22.4%) reported that they struggled to stay awake while driving a car during the past month. As expected, the incidence was higher among night and rotating workers (44%) compared to day (19%) and evening (25%) workers. DSCUSSON Women who worked permanent day shifts were older than those on the other three shifts, particularly the rotating nurses. The rotating shiftworkers were less experienced and worked more hours/week than women working permanent shifts. n comparison with permanent shifts, schedules were less satisfying for rotating shiftworkers, a finding supported by others (7,14). Controversy remains concerning the quantity of sleep obtained by shiftworkers. Some researchers have demonstrated longer sleep periods on days off compared to work days, as found in this study. However, women working permanent night shifts had more hours of sleep on work days and days off than women in the other three groups when incorporating nap time into the total amount of sleep received. Although the total sleep time averaged more than 8.5 hours, nurses in this group perceived that they obtained too little sleep. n a study of German factory workers, length of sleep did not differ according to shift schedule (19). Because the German government does not allow women in industrial jobs to work at night, only male factory workers were compared. A higher percentage of women who worked nights or rotating shifts reported taking naps when compared with day and evening workers. Although there was a trend (p = 0.01) for more night and rotating workers to report use of sleep aids, frequent use was uncommon in all four groups. Contrary to findings in male shiftworkers and other groups (11-13), use of sleep medications, alcohol, and caffeine did not significantly differ among these groups of professional women when age was controlled in the analysis. Because of the significant difference in mean age among the groups, age was entered as a covariate in the ANOV A procedures. Even after controlling for age, the groups differed significantly on a 21-item screening for general sleep disturbances, with night and rotating nurses having higher scores than day and evening nurses. The groups also differed significantly on each dimension of sleep disturbance. t was nurses working Sleep. Vol. 15. No

6 498 K. A. LEE permanent nights and rotating shifts who experienced a higher frequency of problems related to initiating sleep. Although the incidence of difficulty falling asleep was similar for women working permanent day and evening shifts, the rate for the day workers in this study is higher than the 15-17% previously reported for Candian nurses (6). t was the permanent night and rotating nurses who had problems maintaining sleep, problems arousing from the end of a sleep period, and problems maintaining wakefulness. Noise was the overwhelming reason for midsleep awakenings in the permanent night and rotating workers, as also noted in other studies (20). Regardless of shift schedule, more of the younger nurses reported disturbed sleep because of child care responsibilities and more of the older nurses reported disturbed sleep due to snoring, sweats, and hot flashes. Anderson et al. (21) found that of 100 women attending a menopause clinic for complaints of sweats and hot flashes, 77% complained of insomnia that could be characterized by early morning awakenings or interrupted sleep. Presser and Cain (2) report data from the Bureau of Labor Statistics (1980) indicating that an estimated 10 million persons work permanent night shifts or variable shift rotations. t is estimated that 18% of working women rotate shifts (13), but the number of women working permanent night shifts remains unclear. Women in this study reported selecting permanent night shifts because it allowed more options for child care. Additional factors, such as age, socioeconomic status,. tolerance for working at night, childbearing status, and desirability for night shifts because of child care ar- rangements must also be considered when counseling women who work at night or rotate shifts. Additional research is necessary in order to address. the particular developmental stage of a woman and her family when assessing sleep disturbances affecting per- formance in the work place. Although women working in any of these four shift schedules experienced prob- lems initiating, maintaining, and terminating sleep" there were different reasons for these problems when women under 40 years of age were compared to women over 40 years of age. Although the primary reason for sleep disturbance was noise for those who worked per.. manent nights or rotating shifts, much of the distur.. bance was explained by child care responsibilities or reproductive status regardless of the type of shift they worked. Acknowledgements: This study was conducted during a postdoctoral fellowship sponsored by the Robert Wood Johnson Foundation Clinical Nurse Scholars Program. 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