Twenty-four-hour light exposure and melatonin levels among shift workers

Area of Science:

• Occupational Health
• Chronobiology
• Endocrinology

Background:

• Healthcare workers, particularly nurses, often engage in shift work, including rotating day and night shifts.
• Shift work is associated with circadian rhythm disruption and potential adverse health outcomes.
• Melatonin, a key hormone regulating sleep-wake cycles, is sensitive to light exposure.

Purpose of the Study:

• To quantify melatonin levels and 24-hour light intensity exposure in healthcare workers.
• To compare light exposure and melatonin profiles between day workers and rotating shift workers.
• To investigate the correlation between years of shift work and measured light/melatonin levels.

Main Methods:

• Light intensity exposure was recorded for 7-day periods using wearable devices in 22 healthcare workers (5 office workers, 17 nurses).
• Participants completed questionnaires regarding work schedules and years of shift work.
• Saliva samples were collected to measure melatonin levels.

Main Results:

• Rotating shift workers displayed irregular light exposure patterns and altered melatonin levels compared to day workers.
• Rotating shift workers showed decreased melatonin during sleep and increased levels during waking/work periods.
• A positive correlation was found between self-reported years of shift work and measured melatonin and light exposure.

Conclusions:

• Rotating shift work serves as a significant factor contributing to light-at-night exposure.
• The findings support rotating shift work as a model for understanding circadian disruption.
• Interventions targeting light exposure may be crucial for mitigating health risks in shift workers.