Associations Between Salivary Cortisol, DHEA-S, and Alpha-Amylase and Longitudinal Sleep Disruption in Shift-Working Healthcare Professionals: A Pilot Study
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Background
Shift work is a well-established disruptor of sleep, yet the biological mechanisms driving sleep disturbances remain poorly understood. Salivary cortisol (HPA axis), α-amylase (sympathetic– adrenomedullary output), and DHEA-S (adrenal androgen with anti-glucocorticoid/resilience properties) are candidate indicators of stress-related sleep disruption. We therefore examined whether changes in these biomarkers were associated with 6-month sleep trajectories in health professionals.
Methods
In a prospective 6-month repeated-measures design, 52 healthcare professionals (daytime vs. rotating shifts; mean age 31.4 ± 9.4 years; 57% female) completed validated sleep assessments, PROMIS Sleep Disturbance, PROMIS Sleep Impairment, the Sleep-Wake Disorder Index (SWDI), and the NIH 7-day Sleep Diary, at baseline and six-month follow-up. Salivary cortisol, DHEA-S, and alpha-amylase were collected on the morning of Day 7 of each diary period. Change scores (Δ = follow-up – baseline) were computed. Repeated-measures ANOVA, Pearson correlations, and multivariable regressions assessed group differences and biomarker–sleep associations.
Results
Compared with daytime workers, rotating shift workers reported significantly greater increases in sleep disturbance, impairment, and reduced sleep efficiency over time (all p < 0.05). Reductions in cortisol and alpha-amylase were significantly associated with worsening PROMIS Sleep Disturbance and SWDI scores (r = –0.65 and –0.53, respectively; p < 0.05). Multivariable regression showed that decreased cortisol (β = −41.845, p = 0.0064) and increased DHEA-S (β = 0.001, p = 0.0405) associated with worsening PROMIS Sleep Impairment. A combined model including reduced cortisol, and increased DHEA-S associated with greater PROMIS Sleep Disturbance (adjusted R² = 0.698).
Conclusion
In this pilot, changes in salivary cortisol and DHEA-S were associated with longitudinal changes in sleep. These results suggest potential utility for biomarker-informed risk stratification, warranting confirmation in larger, controlled studies.
Plain Language Summary
People working rotating shifts often experience disrupted sleep and chronic stress due to irregular work hours. This study followed a group of rotating shift workers over six months to explore how stress levels, measured through saliva samples, and sleep quality changed over time. Researchers collected data on key stress hormones, including cortisol, alpha-amylase, and DHEA-S, and compared them with both subjective sleep surveys and daily sleep diaries.
The results showed that as stress biomarkers declined, participants reported worse sleep quality and greater impairment in daily functioning. This suggests that when the body’s stress response system becomes weakened, what scientists call “lower cortisol levels” it may be a sign of long-term health strain. These physiological changes mirrored growing sleep disturbances over time.
The findings highlight the importance of monitoring both sleep and biological stress markers in shift workers. Interventions that target better sleep hygiene and stress management may help protect the health of these essential workers. Future studies with larger, more diverse groups are needed to confirm these results and develop personalized strategies to reduce the negative effects of shift work.
