The Effectiveness of Light/Dark Exposure to Treat Insomnia in Female Nurses Undertaking Shift work during the
Evening/Night Shift
Department of Nursing, Chang Gung Memorial Hospital, Linkou, Taiwan; 2Department of Psychiatry, Chang
Gung Memorial Hospital, Linkou, Taiwan; 3Sleep Center, Chang Gung Memorial Hospital, Linkou, Taiwan;
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Chang Gung University College of Medicine, Taoyuan, Taiwan

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S C I E N T I F I C I N V E S T I G AT I O N S

Study Objectives: The present study investigated whether

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keywords:
Commentary:
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Results:

J Clin Sleep Med

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nsomnia is common in the general population. From the review study of Ohayon,1 about one-third of the general population suffers symptoms of insomnia. The prevalence is between 9% and 15% when daytime consequences of insomnia are taken into account. A strong association between insomnia and anxiety/depression is also found in the community and in hospitals.2,3 Chronic insomnia may aggravate the severity of anxiety and depression.4-6 In addition, while insomnia or excessive sleepiness is a risk factor for depression in all individuals, it is a much greater risk factor in rotating or night shift workers.7
Shift work disorder (SWD) is a circadian rhythm sleep disorder characterized by sleepiness or insomnia that can be attributed to the person’s work schedule. According to second

bRIEF SUMMARY

Current knowledge/Study Rationale: Bright light exposure during the

Study Impact:

(ICSD-2),8 the major feature of circadian rhythm sleep disorder is “a misalignment between the patient’s sleep pattern and the sleep pattern that is desired or regarded as the societal norm.”

of the US and 35% of the Taiwan labor force works night, evening, or rotating shifts,9,10 and that 10% of these individuals suffer from SWD.7 Circadian misalignment can be caused by shift work. The resulting circadian misalignment associated

internal clocks and develop SWD due to a mismatch between the sleep/wake schedule required by their jobs and their own circadian sleep/wake cycles. It is estimated that around 20%

with disturbed sleep11,12 and impaired alertness.13,14 The longitudinal study of Bara and Arber15 found that women’s mental health and anxiety/depression were more adversely affected by
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Journal of Clinical Sleep Medicine, Vol. 9, No. 7, 2013

LB Huang, MC Tsai, CY Chen et al

varied shift patterns than by night work. Nurses are the largest working group in a hospital and most are on a rotating shift work schedule. Research has shown that shift work, in particular night work, can have negative effects on the health, safety, and well-being of nurses.16,17 The prevalence of depression is

exposure of 7,000-10,000 lux could be obtained at a distance of around 70 cm from the light box to the nurse. Light intensity was measured using a Lutron Electronic LX-1102 light meter. Ward illumination at night is maintained in the range of 100-400 lux weeks, and daytime outdoor sun exposure after work and before sleep was avoided by the subjects by wearing dark sunglasses with UV protection, including on off-days. The subjects in the

than in day workers.7 Lin et al.18 also found that female nurses who have a rotation shift work schedule tend to experience poor sleep quality and mental health in Taiwan.
Light is the dominant environmental time cue that entrains the human circadian clock to a 24-h day, and the timing of light exposure will determine whether the internal clock is phase delayed or advanced.19 Using this principle, bright light exposure

wore sunglasses to avoid outdoor sun exposure after work and before sleep. Other aspects of lifestyle were not changed, including off-days, in either group. Subjects who used sleep medications did not change the pattern of use across the treatment duration. All participants were reminded of the study procedure by a telephone call before and after