Bioscience trendsSep 15, 2011

Saliva cortisol levels linked to daily blood pressure and heart rate patterns in night shift workers

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Mar 29, 2026

Abstract

Sixteen healthy nurses aged 20-40 participated in a study examining blood pressure, heart rate, and salivary cortisol levels during day and night shifts.

Circadian rhythms in blood pressure and cortisol levels were observed in both day and night shifts.
Clinically significant changes in the timing of blood pressure peaks were noted, but the results were not statistically significant.
A reverse pattern of blood pressure timing was observed in 8 out of 16 subjects when switched to day shifts.
Night shift workers exhibited altered circadian patterns for blood pressure and cortisol, indicating a disruption in their biological rhythms.
Salivary cortisol levels peaked at midnight and increased further in the afternoon during night shifts.
Fatigue levels in night shift nurses may be associated with their disrupted circadian cycle.

Simplified

Recent studies indicate a circadian rhythm in blood pressure and heart rate and its association with various neurotransmitters. In the present study, we examine the circadian nature of blood pressure/heart rate and salivary cortisol in night shift workers and whether these circadian changes produced by night shifts are reversible. Sixteen healthy nurses of both genders, aged 20-40 years, performing day and night shift duties, were randomly selected out of 22 who volunteered for this study. Ambulatory blood pressure monitoring was done in all the subjects and salivary cortisol levels were analyzed during both day and night shift duties. There were clinically significant changes in the Acrophase of blood pressure and cortisol levels, indicating ecphasia (odd timing of systolic blood pressure) individually during night as well as day shifts. However, this pattern was statistically not significant. A reverse pattern of Acrophase was observed in 8 out of 16 subjects when they were posted on day shift. No significant change was found in midline estimating statistics of rhythm (MESOR) of blood pressure values. Changes in Double amplitude (Predictable change) were observed in 8 subjects during night shifts as well as in 7 subjects during day shifts. However, the pattern was not similar and night workers had an altered circadian pattern in the night as well as during day shifts. Changes in Double amplitude, Acrophase and Salivary cortisol were found during night as well as day shifts but these changes were not statistically significant (p > 0.05) due to incomplete recovery during day shifts (changes again seen when they came back to day shifts). Salivary cortisol levels were lowest in early morning, increased at midnight and further increased in the afternoon during night shifts along with ecphasia. It is possible that nurses working the night shift felt more tired due to the altered circadian cycle.

Saliva cortisol levels linked to daily blood pressure and heart rate patterns in night shift workers

Abstract

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

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