Shaping the light/dark pattern for circadian adaptation to night shift work

Healthy young subjects (n=31) showed a delay in dim light melatonin onset (DLMO) to approximately 00:00-1:00 after three night shifts with bright light exposure.

• The target DLMO of approximately 3:00 was not fully achieved, but progress was made toward this goal.
• Experimental groups receiving bright light pulses performed better on a reaction time task during night shifts compared to the control group.
• Control subjects exhibited little change in DLMO from baseline, indicating limited adjustment to night shift conditions.
• Intermittent bright light exposure, dark bedroom conditions, and scheduled sleep may support circadian phase adjustment.
• Future studies are planned to assess the maintenance of the target circadian phase with continued night shifts and days off.

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