Light Treatment to Shift-working Nurses

Study Overview
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Brief Summary
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This project examines 1) the effects of appropriately timed bright light on adaptation (in terms of sleep and sleepiness) to three consecutive night shifts; and 2) the effects of such bright light on re-adaptation (in terms of sleep and sleepiness) to a day-oriented schedule after the night shift period.

Detailed Description
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Shift workers frequently experience sleepiness during night shifts, which may have consequences for performance. Sleep duration is often shortened after a night shift. Properly timed bright light treatment is efficient in delaying the circadian rhythm and can enhance alertness, increase performance and prolong sleep after night shifts. There is a lack of studies on light treatment to rotating shift workers. This study is a randomized controlled crossover trial evaluating the effect of bright light treatment on sleep and sleepiness in rotating shift workers with three consecutive night shifts. The aim is to evaluate whether bright light treatment improves adaptation to three consecutive night shifts (reduces sleepiness during night shifts and improves sleep after night shifts), as well as whether such treatment affects re-adaptation to a day-oriented schedule after the night shift period.

Official Title
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The Effects of Bright Light on Adaptation to Night Work Among Nurses

Conditions
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Shift-Work Sleep Disorder

Intervention / Treatment
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* Behavioral: Bright light
* Behavioral: Red light


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: A rotating shift work schedule involving three days without night shifts, followed by three consecutive night shifts, followed by three days without night shifts Problems with sleepiness during night shifts Exclusion Criteria: Pregnancy

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Bright light<br>10 000 lux | Behavioral: Bright light<br>* Bright light for 30 minutes during night shifts (between 2 AM and 3 AM the first night, between 3 AM and 4 AM the second night, between 4 AM and 5 AM the third night).<br>|
| Placebo Comparator: Red light<br>400 lux | Behavioral: Red light<br>* Red light for 30 minutes during night shifts (between 2 AM and 3 AM the first night, between 3 AM and 4 AM the second night, between 4 AM and 5 AM the third night).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sleepiness during the night shifts | Self-reported using the Karolinska Sleepiness Scale (KSS) | 3 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Psychomotor vigilance during night shifts | Objective data from a 5 min computer based psychomotor vigilance test (PC-PVT) taken once during each night shift | 3 days | 
| Sleep after the night shifts | Self-reported using a sleep diary; objective data from actigraphs | 3 days | 
| Sleepiness during the days after the night shift period | Self-reported using the Karolinska Sleepiness Scale (KSS) | 3 days | 
| Sleep during the days after the night shift period | Self-reported using a sleep diary; objective data from actigraphs | 3 days | 
| Functioning on each shift, and shift period in total, compared to under normal conditions | Self-reported perception of effect of intervention | 6 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Bright light, Sleepiness, Sleep, Psychomotor vigilance