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.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
35
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).
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).
University of Bergen
Bergen, Hordaland, Norway
Sleepiness during the night shifts
Self-reported using the Karolinska Sleepiness Scale (KSS)
Time frame: 3 days
Psychomotor vigilance during night shifts
Objective data from a 5 min computer based psychomotor vigilance test (PC-PVT) taken once during each night shift
Time frame: 3 days
Sleep after the night shifts
Self-reported using a sleep diary; objective data from actigraphs
Time frame: 3 days
Sleepiness during the days after the night shift period
Self-reported using the Karolinska Sleepiness Scale (KSS)
Time frame: 3 days
Sleep during the days after the night shift period
Self-reported using a sleep diary; objective data from actigraphs
Time frame: 3 days
Functioning on each shift, and shift period in total, compared to under normal conditions
Self-reported perception of effect of intervention
Time frame: 6 days
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