The Effects of Sleep Restriction on Urinary and Salivary Cortisol Levels

Open Access
Meka, Venkata Sai
Area of Honors:
Biobehavioral Health
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Dr. Orfeu M. Buxton, Thesis Supervisor
  • Dr. Lori Anne Francis, Honors Advisor
  • cortisol
  • sleep restriction
  • urinary cortisol
  • salivary cortisol
  • stress
  • sleep health
Sleep deprivation is a serious issue which affects many individuals in an increasingly hectic day and age. Not prioritizing sleep can lead to host of negative health outcomes, including hormonal dysregulation. Excessively increased or decreased levels of cortisol, in particular, can have adverse effects on the body through changes to the hypothalamic adrenal axis. Consequently, this study sought to understand how sleep restriction could impact the levels of urinary and salivary cortisol. This was accomplished by recruiting subjects for an 11-day inpatient study performed at the Pennsylvania State University Clinical Research Center. Three sleep conditions were observed: three days of baseline (10 hours of sleep opportunity), five days of sleep restriction (5 hours of sleep opportunity) and one day of recovery (10 hours of sleep opportunity). Hourly saliva samples and 24-hour urine samples were taken throughout and analyzed via the DRG Urinary Cortisol Assay Kit and the Salimetrics Cortisol Assay Kit respectively. The results for both urinary and salivary cortisol showed flat and blunted lines not indicative of sleep restriction. Comparing the two measures against each other, there was no association seen across most of the subjects and a slight negative association for a few. Limitations such as the small sample size and interference from other procedures could be remedied in the future while implementing new methods of measuring cortisol.