On-shift naps are associated with systolic and diastolic blood pressure level among night working nursing professionals.

Few studies have analyzed on-shift naps with regard to shift workers' health. The aim of this study was to examine the association between exposure to night work (intensity and length of exposure to night work) and blood pressure (BP), considering the impact of on-shift naps. A cross-sectional study was carried out at a hospital based on a questionnaire and measurement of BP. The outcomes were systolic blood pressure (SBP), diastolic blood pressure (DBP), and casual hypertension (HTN), i.e., SBP > 140 mmHg, or DBP > 90 mmHg, or reporting a prescription of antihypertensive medication. The sample comprised 449 fixed 12 h night workers who were (unofficially) allowed to nap during the night shift for up to 3 h. Approximately 42% of the sample reported napping. Among non-nappers (but not among nappers), those exposed to more work nights (≥5/fortnight) showed a DBP that was 3.66 mmHg higher than that of the reference group. The likelihood of casual HTN was more than three-fold greater among non-nappers working more nights/fortnight than among those working fewer nights/fortnight. A similar tendency was observed in a subsample of workers who did not take antihypertensive medication. The results were less consistent regarding length of exposure to night work (in years). A possible explanation is that workers who usually take on-shift naps could experience suppression of the BP increase derived from the many nights worked, while the non-nappers did not experience this suppression. The results may be explained by the relationship between napping, melatonin secretion, and attenuation of circadian misalignment. Napping likely contributes to creating a "physiologically nocturnal environment" that tends to favor the circadian system and, therefore, health. Possible negative effects related to sleep inertia deserve attention. The findings encourage new studies on this topic to improve the management of night work at hospitals in regard to workers' health.