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Scheduled evening sleep and enhanced lighting improve adaptation to night shift work in older adults
  1. Evan D Chinoy1,2,3,
  2. Michael P Harris1,
  3. Min Ju Kim1,2,4,
  4. Wei Wang1,2,
  5. Jeanne F Duffy1,2
  1. 1Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, Massachusetts, USA
  2. 2Division of Sleep Medicine, Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
  3. 3Warfighter Performance Department, Naval Health Research Center, San Diego, California, USA‡
  4. 4Department of Neurology, Davos Hospital, Yongin, Korea‡
  1. Correspondence to Dr Jeanne F Duffy, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, 221 Longwood Avenue, BLI-438, Boston, MA 02115, USA; jduffy{at}research.bwh.harvard.edu

Abstract

Objectives We tested whether a sleep and circadian-based treatment shown to improve circadian adaptation to night shifts and attenuate negative effects on alertness, performance and sleep in young adults would also be effective in older adults.

Methods We assessed subjective alertness, sustained attention (psychomotor vigilance task, PVT), sleep duration (actigraphy) and circadian timing (salivary dim-light melatonin onset, DLMO) in 18 older adults (57.2±3.8 years; mean±SD) in a simulated shift work protocol. 4 day shifts were followed by 3 night shifts in the laboratory. Participants slept at home and were randomised to either the treatment group (scheduled evening sleep and enhanced lighting during the latter half of night shifts) or control group (ad-lib sleep and typical lighting during night shifts).

Results Compared with day shifts, alertness and sustained attention declined on the first night shift in both groups, and was worse in the latter half of the night shifts. Alertness and attention improved on nights 2 and 3 for the treatment group but remained lower for the control group. Sleep duration in the treatment group remained similar to baseline (6–7 hours) following night shifts, but was shorter (3–5 hours) following night shifts in the control group. Treatment group circadian timing advanced by 169.3±16.1 min (mean±SEM) but did not shift (−9.7±9.9 min) in the control group.

Conclusions The combined treatment of scheduled evening sleep and enhanced lighting increased sleep duration and partially aligned circadian phase with sleep and work timing, resulting in improved night shift alertness and performance.

  • aging

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