Associations between shift work arrangements, sleep characteristics, urinary cortisol and melatonin levels among nurses in Hong Kong

Sep 3, 2025Occupational and environmental medicine

Shift work schedules, sleep patterns, and stress and sleep hormone levels in Hong Kong nurses

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

PAN pattern nurses slept 5.8 hours on average, compared to 6.4 hours for non-PAN nurses.

Nurses with rapid-rotating PAN shifts exhibited a greater circadian phase delay of 16.4 hours compared to 15.9 hours in non-PAN nurses.
Cortisol levels were significantly lower in non-PAN nurses (β=-0.31, p=0.017) compared to daytime workers.
Each additional hour of sleep was associated with a 10.3% decrease in cortisol levels.
Later wake-up times were linked to a 3.9% reduction in cortisol levels, while delayed sleep midpoints decreased melatonin by 5.1% per hour.
A three-way interaction suggested that the relationship between cortisol levels and sleep duration weakened with later wake-up times in PAN nurses.

AI simplified

OBJECTIVES: Shift work disrupts hormonal rhythms, but evidence linking specific shift patterns to cortisol/melatonin variations remains limited. This study evaluated the associations of a rapid-rotating shift pattern (ie, PAN pattern, shift transitions from afternoon to morning to night shifts within approximately 40 hours) and irregular non-PAN pattern shifts with urinary cortisol and melatonin among Hong Kong nurses, while also assessing the role of sleep on rhythmic hormones.

METHODS: A 7-day actigraphy-based study recruited 201 shift nurses and 100 daytime workers. First-morning voids on the first non-workday postnight shift or postoffice work measured cortisol and melatonin metabolite (aMT6s) levels. Actigraphy measured sleep parameters. Generalised linear models examined the associations.

RESULTS: PAN pattern nurses slept less than non-PAN nurses (5.8 vs 6.4 hours) and exhibited greater circadian phase delay (16.4 vs 15.9 hours). Non-PAN nurses had the lowest cortisol, cortisone and aMT6s levels, with significantly reduced cortisol levels (β=-0.31, p=0.017) compared with daytime workers. Sleep characteristics strongly influenced hormone levels, with each additional hour of sleep decreasing cortisol levels by 10.3%, while each later hour of wake-up time was associated with 3.9% lower cortisol levels; later sleep midpoints decreased melatonin by 5.1% per hour. A three-way interaction revealed weakened cortisol-sleep duration associations with later wake-up times in PAN nurses (p=0.032).

CONCLUSIONS: Irregular shifts, longer sleep duration and delayed wake-up time significantly reduced wakening cortisol levels, while delayed sleep timing suppressed melatonin secretion. These findings highlight how shift arrangements and sleep characteristics disrupt hormonal rhythms in shift workers. Optimising shift patterns and sleep interventions (eg, prioritising duration/consistency) may mitigate circadian disruption and improve shift worker health.

Full Text

Full text is available at the source.

View full text ↗

Associations between shift work arrangements, sleep characteristics, urinary cortisol and melatonin levels among nurses in Hong Kong

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief