• 沒有找到結果。

Sleep Quality and Morningness-Eveningness on Shift Nurses

N/A
N/A
Protected

Academic year: 2021

Share "Sleep Quality and Morningness-Eveningness on Shift Nurses"

Copied!
1
0
0

加載中.... (立即查看全文)

全文

(1)

Sleep Quality and Morningness-Eveningness on Shift Nurses

Min-Huey Chung1, 2; Fu-Mei Chang, RN, PhD3; Cheryl C. H. Yang, PhD4;Terry B. J. Kuo, MD, PhD4; Nanly Hsu, RN, PhD3

1Institute of Medical Sciences, Tzu Chi University, Hualien; 2School of Nursing,

National Defense Medical Center, Taipei, Taiwan. 3 School of nursing, Tzu Chi

University, Hualien; 4 Institute of Brain Science, National Yang-Ming University,

Taipei, Taiwan.

Running Title: morningness-eveningness on sleep quality –Chung et al. Keywrods: shift, nurse, morningness-eveingness, sleep

Address correspondence to: Nanly Hsu, School of Nursing, Tzu Chi University, No. 701, Chung Yang Road, Section 3, Hualien 97004, Taiwan; Tel: 886 3 8565301 (ext.7034); Fax: 886 3 8580639; E-mail: nlhsu@mail.tcu.edu.tw

(2)

ABSTRACT

Aim and objective. The aim of the study was to analyze, while controlling for identified covariates, the effects of morningness-eveningness on global sleep quality and components of sleep quality for shift nurses.

Background. Shift nurses had greater difficulty falling asleep or staying asleep, thus resulting in higher rates of retiring from hospital. Existing research has addressed the effects of manpower demand and personal preferences on shift assignment; however, the concept of endogenous rhythms is considered rarely.

Methods. This analysis included 137 nurses between the ages of 21 and 47. Nurses completed the Horne and Ostberg questionnaire to assess morningness-eveningness and the Pittsburgh Sleep Quality Index (PSQI) questionnaire to measure self-reported sleep quality over the last month. The 18-point Chinese version had a Cronbach’s reliability coefficient of 0.79 overall and 0.86, respectively. This study analyzed correlates of sleep quality by comparing the groups with better or worse sleep quality according to the median of PSQI. Univariate and multivariate analyses were used for the risk factors of worse sleep quality.

Results. The result showed that the strongest predictor of sleep quality was morningness-eveningness not the shift schedule or shift pattern for nurses under controlling the variable of age. Greater age and longer years employed in nursing significantly decreased the risk of worse sleep quality. The confounding age factor

(3)

was properly controlled; evening types working on shifting jobs had higher risk of poor sleep quality compared to morning types.

Conclusion. Morningness-eveningness was the strongest predictor of sleep quality under controlling the variable of age in shift nurses.

Implications for clinical practice. Our results suggested that determining if nurses were attributed to morning or evening types is an important sleep issue before deciding the shift assignment.

(4)

Introduction

Nurses work under a shift work system (day shift, evening shift and night shift) in response to patient needs. The shift work system disturbs the natural human circadian rhythm and causes lack of sleep (Knauth et al. 1980), which directly or indirectly lowers work efficiency. According to the stressor model by Olsson et al.(1990) stressors brought by the shift system are occupational stressors, personal factors, and non-occupational stressors. Occupational stressors included the shift system (speed and hours) and workload. Personal factors consisted of sex, age, and circadian rhythm types. Non-occupational stressors involved the level of stress in daily living. These stressors cause tremendous pressure on shift workers and arouse physical and psychological reaction; furthermore, they cause sleep disturbances and circadian rhythms disorders. At last, the health of these workers is under duress and the vicious cycle may cause nurses to quit their jobs. Therefore, it is necessary to continuously study nurses’ work shift system.

The effect of shift work on worker health is determined by personal factors; for instance, the individual biological clock and circardian rhythm. Brain resititution and sleep are influenced by personal inner factors, such as age, circardian rhythm, physical condition and flexible sleep habits. In other words, the shift worker tends to adjust his own schedule, especially sleep habits. Gander et al. (1993) studied the shift

(5)

work problems of pilots and indicated that age and circardian rhythm were the main factors contributing to work shift assignment and fatigue. Age, circardian rhythm type and sleep disturbance effectively influence work performance. The circardian rhythm types could be categorized as Morning-types (M-types), Evening-types (E-types)and in between the Intermediate type. The M-types get up early and sleep early, while the E-types are active during the night and can not get up early.

Shift assignement is decided mainly by the manpower demands in hospital wards and personal preferences; but the endogenous rhythm concept is not considered. Most studies examined the effect of shift work on sleep (Coffey et al. 1988; Niedhammer et

al. 1994; Poissonnet & Veron 2000; Skipper et al. 1990) or focused on examining

correlates of simulated shift work (Cajochen et al. 1995; Dijk et al. 1991; Finelli et al. 2000). Few studies focused on the effects of morningness-eveningness on sleep quality, particularly in practical shiftwork nurses. We studied the sleep pattern of five different work shifts, including day shift (07:30-15:30), evening shift (15:30-23:30), night shift (23:30-07:30), day shift to evening shift or night shift (fast clockwise), and night shift to day shift or evening shift (fast counter-clockwise). The aim of the study was to analyze, while controlling for identified covariates, the effects of morningness-eveningness on global sleep quality and components of sleep quality for shiftwork nurses. The result may serve as a reference for work shift assignment.

(6)

Method

The present analysis included 137 nurses between the ages of 21 and 58 enrolled in the total. Seventy-four subjects were in their twenties, 42 subjects were in their thirties and 21 subjects were between the ages of 40 and 58. All subjects were screened to be clear of any personal history of psychiatric, neurological, sleep or medical disorders. Subjects read and signed an informed consent that provided detailed information about the nature, propose and risks of this study.

The personnel in each ward were informed about the study orally by the author at three different personnel meetings. A contact person at each casualty department was selected to answer any questions about the study. After the informed consent was obtained from all women, the researcher would check the missing data to ask nurses fill it again. The PSQI (Buysse et al. 1989) is a questionnaire that measures self-reported sleep habits over the last month. It is a global measure with seven components; perceived sleep quality, sleep latency, sleep duration, sleep efficiency, sleep disturbance, use of sleep medication, and daytime dysfunction. The score for each component ranges from 0 to 3, and the sum is a global score that ranges form 0 to 21. As those who took sleep medication were excluded, only six components were used, with global scores form 0 to 18. Higher scores indicated poorer sleep quality. Both the global PSQI and the component subscale scores were analyzed so that effects

(7)

of music on individual elements of sleep could be determined.

A score of 5 (indication poor sleep) yield a diagnostic sensitivity of 89.5% and a specificity of 86.55, with an internal consistency of α =0.83, and test-retest reliability, r=0.85(Buysse et al. 1989). The Chinese language of PSQI had α =0.72 and a split half reliability of 0.84(Wang 1997). In this study, the 18-point Chinese version had a Cronbach’s reliability coefficient of 0.79 overall and a split half reliability of 0.74 for the six component scores. Using instrument translated into Chinese, several variables were measured on their duty to determine whether they would confound the effects of morningess-eveningness on sleep.

Participants were asked whether or not they had a bedtime routine, napped after lunch, used herbal tea to sleep. Heart rate and blood pressure were measured by the investigator in the first visit. Subjects completed the Horne and Ostberg (1976) questionnaire in order to assess the morningness-eveningness. This questionnaire establishes five behavioral categories (English version scoring): definitively morning types (score=28-32), moderately morning types (score=23-27), neither types (score=16-22), moderately evening types (score=11-15) and definitively evening types (score=6-10). For the purpose of this study we reduced the categories from five to three: morning type (score=23-32), neither type (score=16-22) and evening type (score=6-15).

(8)

For maximizing the statistical power, worse sleep quality was defined by being higher than the median of PSQI (8). For basic comparisons, socio-demographic characteristics, feature of nursing work nature (years of duty, shift schedule, and shifting pattern), blood pressure, tea/coffee drinking habit and morningness-eveningness type were statistically examined by using t-tests for continuous variables and Chi-square tests for categorical variables. The major area of interest for worse sleep quality was the morningness-eveningness type for nurses with shifting work hours. Other factors were considered as potential confounders in the advanced statistical explorations in this study. Afterwards, we utilized univariate logistic regressions to estimate the relative risk of each variable on worse sleep quality. After that, potential confounders were involved in constructing the final model of detecting the effect of morningness-eveningness type for sleep quality among nurses. To explore which components would be sensitive to individual morningness-eveningness types of the nurses, we performed linear regressions by separating PSQI components to detect the effect of morningness-eveningness type for each component. SPSS 12.0 for Windows was utilized to perform all the statistical analyses and the significance level (P value) was set as 0.05.

Results

(9)

the results from comparing the baseline of two groups. Age, years of duty, and morningness-eveningness types were significantly different between the groups with and without worse sleep quality. Specifically, older nurses and longer employment duration showed decreased risk for worse sleep quality (OR = 0.93, 95% CI: 0.89-0.98; OR = 0.95, 95% CI: 0.90-0.99, respectively). It was noteworthy that E- types revealed a significantly increase risk of worse sleep quality (OR = 6.56, 95% CI: 1.89-22.88). None of the other risk factors showed a significant effect on sleep quality, in terms of PSQI (Table 2). For precise estimation of the effects in our study (morningness-eveningness type), confounding control was achieved for age and years of duty. Because of the collinearity between age and years of duty, their 95% CIs were widened and the statistical significance lost in multivariate analyses. Thus, in Table 3, we decided to control the age as the only confounder and achieved the best relative risk estimation for morningness-eveningness types (evening type OR = 3.88, 95% CI: 1.01-14.90, relative to morning type). Consequently, when age was properly controlled, E-type nurses working on shifting jobs had a higher risk for poor sleep quality. To further explore the PSQI components, the scores of component 1 (subjective sleep quality) and Component 3 (sleep duration) were significantly raised for E-type nurses. Namely, nurses with evening type had apparent poor subjective sleep quality rating and their percentage of sleep time within the total number of hours

(10)

in bed was significantly lower than the ones of morning type.

Discussion

This study was employed questionnaires to measure morningness-eveningness and sleep quality of shift nurses. It was to analyze correlates of sleep quality by comparing these groups with better or worse sleep quality according to the median of PSQI (8). Univariate and multivariate analyses were used to identify the risk factors of worse sleep quality. The result showed that the strongest predictor of sleep quality was the subject’s natural morningness-eveningness sleep pattern not the shift schedule or shift pattern. Although this result could not confirm the relationship of cause and effect in sleep quality, we indicated that considering morningness-eveningness type of nurses was an important issue for sleep quality in rotating shift nurses.

The study found a significant change in age and years of duty on sleep quality in shift nurses (table 1). This result was consistent with previous studies(Carrier et al. 1997). After further analyzing the results, we found that older age and longer years of duty decreased the risk of worse sleep quality. This result was not in line with that increasing age associated with less time asleep or increased number of awakenings during the sleep period(Carrier et al. 1997). However, this result was consistent with no age effect on habitual sleep length, bedtime or wakening (Ishihara et al. 1992). According to Harma (1993) greater tolerance to shift work was related with more

(11)

control hours of work through individual choice with regard to shift system acceptability. This study may imply that more experienced nurses could have greater tolerance to shift work, which allows them sleep well.

M-types show a preference for waking at an early hour and experience alertness early in the day. E-types show a preference for sleeping at latter hours and function better in the afternoon and evening (Giannotti et al. 2002). Previous studies indicated that E-types find adjustment to night shifts easier (Paine et al. 2006). Therefore, it is better to understand the effect of morningness/eveingness on sleep quality for nurses before knowing their acceptability and adjustment to shift work. This study surveyed the relationship among morningness-eveningness type, shift pattern and sleep quality. We differentiated the shift schedule by checking the nurse’s actual duty time to make the shift pattern parameter more precise. This result showed that shift schedule or shift pattern was not correlated with sleep quality. However, the sleep quality was correlated with morningness-eveningness. This finding may hint nurses working at night or arranging shift schedule should assess their endogenous type (morningness and eveningness) at first. Whether shift work reflects morningness-eveingness sleep habit or it influence shift work is interesting and warrants further exploration.

We found that E-type nurses had worse sleep quality compared to M-types. Especially, nurses with evening type reflected negative extremes on two areas:

(12)

subjective sleep quality and sleep duration; however, changes declined on the rest five areas: sleep latency, habitual sleep efficiency, sleep disturbances, use of sleeping medication and daytime dysfunction. These findings may be explained as follows: First, E-types tend to vary considerably their sleep/ waking time and sleep length (Ishihara et al. 1992; Kerkhof 1985; Monk et al. 1994). They delayed their sleep wake schedules more than morningness type. This study showed that E-types sleep from 1AM to 4 AM and wake up from 10AM to 2PM, while M-types sleep from 10 PM to 12 PM and wake up from 6AM to 8AM in the day shift and off duty time. We confirmed that E-types had more changeable sleep-wake schedules than M-types. Second, E-types were related with a greater need for sleep (Taillard et al. 1999). This study indicated the sleep length of E-types around 5 hours to 8 hours in the day shift and evening shift, but around 10 to 12 hours in their days off. E-types had more irregular sleep-waking time, this situation resulted in a sleep debt during their day shift and extended their sleep duration in their off time.

We analyzed correlates of sleep quality and tried to understand changes of morningness-eveningness for shiftwork nurses as a reference. A longitudinal survey would propose more efficient suggestions. We hope that shift problems of doctors and pharmacists should be studied in the future study.

(13)

Acknowledgements

This study was supported by Tri-service General Hospital Foundation in Taiwan (Research Grant TSGH-C94-095).

References

Buysse DJ, Reynolds CF, 3rd, Monk TH, Berman SR & Kupfer DJ (1989) The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res 28, 193-213.

Cajochen C, Brunner DP, Krauchi K, Graw P & Wirz-Justice A (1995) Power density in theta/alpha frequencies of the waking EEG progressively increases during sustained wakefulness. Sleep 18, 890-894.

Carrier J, Monk TH, Buysse DJ & Kupfer DJ (1997) Sleep and morningness-eveningness in the 'middle' years of life (20-59 y). J Sleep Res 6, 230-237. Coffey LC, Skipper JK, Jr. & Jung FD (1988) Nurses and shift work: effects on job

performance and job-related stress. J Adv Nurs 13, 245-254.

Dijk DJ, Brunner DP & Borbely AA (1991) EEG power density during recovery sleep in the morning. Electroencephalogr Clin Neurophysiol 78, 203-214.

Finelli LA, Baumann H, Borbely AA & Achermann P (2000) Dual

electroencephalogram markers of human sleep homeostasis: correlation between theta activity in waking and slow-wave activity in sleep.

Neuroscience 101, 523-529.

Gander PH, DE nguyen BE, Rosekind MR & connell LJ (1993) Age, circadian rhythms, and sleep loss in flight crews. Avitation, Space and Evironmental

Medicine 64, 189-195.

Giannotti F, Cortesi F, Sebastiani T & Ottaviano S (2002) Circadian preference, sleep and daytime behaviour in adolescence. J Sleep Res 11, 191-199.

Harma M (1993) Individual differences in tolerance to shiftwork: a review.

Ergonomics 36, 101-109.

Ishihara K, Miyake S, Miyasita A & Miyata Y (1992) Morningness-eveningness preference and sleep habits in Japanese office workers of different ages.

Chronobiologia 19, 9-16.

Kerkhof GA (1985) Inter-individual differences in the human circadian system: a review. Biol Psychol 20, 83-112.

(14)

Duration of sleep depending on the type of shift work. Int Arch Occup

Environ Health 46, 167-177.

Monk TH, Petrie SR, Hayes AJ & Kupfer DJ (1994) Regularity of daily life in relation to personality, age, gender, sleep quality and circadian rhythms. J

Sleep Res 3, 196-205.

Niedhammer I, Lert F & Marne MJ (1994) Effects of shift work on sleep among French nurses. A longitudinal study. J Occup Med 36, 667-674.

Olsson K, Kandolin I & Kauppinen-Toropainen K (1990) Stress and coping strategies of three-shift workers. Le Travail Humain 53, 213-226.

Paine SJ, Gander PH & Travier N (2006) The epidemiology of

morningness/eveningness: influence of age, gender, ethnicity, and socioeconomic factors in adults (30-49 years). J Biol Rhythms 21, 68-76. Poissonnet CM & Veron M (2000) Health effects of work schedules in healthcare

professions. J Clin Nurs 9, 13-23.

Skipper JK, Jr., Jung FD & Coffey LC (1990) Nurses and shiftwork: effects on physical health and mental depression. J Adv Nurs 15, 835-842.

Taillard J, Philip P & Bioulac B (1999) Morningness/eveningness and the need for sleep. J Sleep Res 8, 291-295.

Wang YW (1997) Effect of Acupressure on the sleep disturbance of Taiwanese elderly. Unpublished doctoral dissertation Case Western Reserve University, Cleveland.

(15)

Table 1 Basic characteristics and comparisons of the groups with better or worse sleep quality by the median of PSQI (N= 137)

Variables Worse sleep quality(PSQI ≧ 8)(n=75) Better sleep quality(PSQI < 8)(n=62) P value^

Age (mean ± SD) 28.57 ± 7.28 33.05 ± 8.94 <0.01*

Years employed in nursing

(mean ± SD) 6.59 ± 6.57 9.59 ± 8.28 <0.05*

BMI (mean ± SD) 21.22 ± 3.06 21.52 ± 2.96 0.62

Systolic blood pressure (mean

± SD) 112.69 ± 10.30 124.37 ± 10.30 0.41

Diastolic blood pressure (mean

± SD) 67.39 ± 9.28 68.08 ± 9.41 0.71

Heart beat rate (mean ± SD) 80.02 ± 10.09 77.16 ± 7.05 0.10 Marriage status Single Married Divorced 47 26 2 34 27 1 0.54 Frequency of tea Never < Once a week 1-2 times a week 3-4 times a week 5-7 times a week 18 15 15 13 14 20 8 11 10 13 0.72 Frequency of coffee Never < Once a week 1-2 times a week 3-4 times a week 5-7 times a week 32 13 11 9 10 21 7 11 6 17 0.26 Health supplement No Yes Missing 51 23 1 40 20 2 0.73 Shift schedule Fixed Shifting 2352 2438 0.32 Shifting pattern Fast clockwise Fast counter-clockwise Slow shifting Others 27 1 23 24 25 3 12 22 0.33 Morningness-eveningness type Morning type Neither type Evening type 8 46 21 15 41 6 <0.05*

(16)

^ Independent t-tests for continuous variables and Chi-square tests for categorical variables

(17)

Table 2 Univariate analyses for the risk factors of worse sleep quality (PSQI ≧ 8) by logistic regressions (N= 137)

Variables OddsRatio 95 % Confidence Interval P value^

Age 0.93* 0.89 – 0.98 <0.01*

Years employed in nursing 0.95* 0.90 – 0.99 <0.05*

BMI 0.97 0.85 – 1.10 0.62

Systolic blood pressure 0.98 0.95 – 1.02 0.41

Diastolic blood pressure 0.99 0.95 – 1.04 0.71

Heart beat rate 1.04 0.99 – 1.09 0.10

Marriage status Single Married Divorced Ref 0.70 1.45 --0.35 – 1.40 0.13 – 16.61 0.310.77 Frequency of tea Never < once a week 1-2 times a week 3-4 times a week 5-7 times a week Ref 2.08 1.51 1.44 1.20 --0.72 – 6.07 0.55 – 4.14 0.51 – 4.09 0.45 – 3.21 0.18 0.42 0.49 0.72 Frequency of coffee Never < once a week 1-2 times a week 3-4 times a week 5-7 times a week Ref 1.22 0.66 0.98 0.39 --0.42 – 3.56 0.24 – 1.79 0.31 – 3.17 0.15 – 1.00 0.72 0.41 0.98 0.05 Health supplement No Yes Missing Ref 0.90 0.39 --0.44 – 1.87 0.03 – 4.48 0.780.45 Shift schedule Fixed Shifting Ref1.43 --0.70 – 2.90 0.32 Shifting pattern Fast clockwise Fast counter-clockwise Slow shifting Others Ref 0.31 1.78 1.01 --0.30 – 3.17 0.73 – 4.30 0.46 – 2.24 0.32 0.20 0.98 Morningness-eveningness type Morning type Neither type Evening type Ref 2.10 6.56* --0.81 – 5.47 1.89 – 22.88 0.13<0.01* * Statistical significance

(18)

Table 3 Multivariate analysis for the risk factors of worse sleep quality (PSQI ≧ 8) by logistic regression (Total number of subjects: 137), controlled for age

Variables OddsRatio 95 % Confidence Interval p value^

Age^ 0.95* 0.91 – 0.99 <0.05* Morningness-eveningness type Morning type Neither type Evening type Ref 1.58 3.88* --0.58 – 4.35 1.01 – 14.90 0.37<0.05* * Statistical significance

(19)

Table 4 The effect of morningness-eveningness type by each component of Pittsburgh Sleep Quality Index (PSQI) with linear regressions, adjusted by age (N=137)

Components of PSQI B value 95 % Confidence Interval P value^

Subjective sleep quality Morning type Neither type Evening type Ref 0.32 0.65* ---0.01 – 0.64 0.24 – 1.06 0.06 <0.01* Sleep latency Morning type Neither type Evening type Ref 0.25 0.27 ---0.59 – 1.08 -0.78 – 1.33 0.560.61 Sleep duration Morning type Neither type Evening type Ref 0.39 0.89* ---0.03 – 0.81 0.36 – 1.42 0.07<0.01* Habitual sleep efficiency

Morning type Neither type Evening type Ref 0.06 0.51 ---0.46 – 0.59 -0.15 – 1.18 0.810.13 Sleep disturbances Morning type Neither type Evening type Ref -0.09 0.08 ---0.35 – 0.16 -0.24 – 0.40 0.480.62 Use of sleep medication

Morning type Neither type Evening type Ref 0.11 0.21 ---0.24 – 0.45 -0.23 – 0.64 0.540.36 Daytime dysfunction Morning type Neither type Evening type Ref 0.09 0.10 ---0.32 – 0.49 -0.41 – 0.61 0.680.71 * Statistical significance

數據

Table 1 Basic characteristics and comparisons of the groups with better or worse sleep quality by the median of PSQI (N= 137)
Table 2 Univariate analyses for the risk factors of worse sleep quality (PSQI ≧ 8) by logistic regressions (N= 137)
Table 3 Multivariate analysis for the risk factors of worse sleep quality (PSQI ≧ 8) by logistic regression (Total number of subjects: 137), controlled for age
Table 4 The effect of morningness-eveningness type by each component of Pittsburgh Sleep Quality Index (PSQI) with linear regressions, adjusted by age (N=137)

參考文獻

相關文件

[r]

In the course of QA inspection, assessment of the quality of the learning and teaching of individual subjects

Microphone and 600 ohm line conduits shall be mechanically and electrically connected to receptacle boxes and electrically grounded to the audio system ground point.. Lines in

Subsequently, the relationship study about quality management culture, quality consciousness, service behavior and two type performances (subjective performance and relative

This shows that service quality, perceived value, DM advertising, customer satisfaction and loyalty have become important issues on business management.. Therefore, the

Followed by the use of an important degree of satisfaction with the service quality attributes, by Kano two-dimensional quality model, IPA analysis and

The analytic results show that image has positive effect on customer expectation and customer loyalty; customer expectation has positive effect on perceived quality; perceived

In terms of external cognitive factors, this research confirmed that assurance, apathy and price reasonability as part of the service quality dimension have influence on