Cortisol levels may not be rising just on waking up as previously thought, rather they are already on the rise as the body gets ready for the day ahead, according to a new research.
Researchers, led by those at the University of Bristol in the UK, found that cortisol levels increase in the hours prior to awakening as part of the body’s preparation for the day ahead, so waking up may not be as “stressful” as previously thought, they said.
Known as the ‘stress hormone’, cortisol’s levels vary through the day in sync with one’s 24-hour cycle, increasing in response to stress to help the body manage it.
Waking up after a night’s sleep is considered to trigger cortisol production and is termed the ‘cortisol awakening response’—something that has been previously studied in varied contexts, including Post-Traumatic Stress Disorder, obesity and depression.
However, this study, published in the journal Proceedings of the Royal Society B: Biological Sciences, suggests that if cortisol has any relationship with waking up, it is with the factors contributing to the initiation of awakening rather than being a response to it, the authors said.
They added that previous studies analysing the cortisol response have typically assessed saliva samples obtained after waking up, not in the period prior to this.
Consequently, the studies are not able to prove a change in the rate of cortisol secretion over the awakening period, the researchers said.
In this study, the team measured cortisol levels both before and after waking up in over 200 healthy men and women, aged 18-68 years, using an automated system.
“We found no evidence for a change in the rate of cortisol increase in the hour after waking when compared with the hour prior to waking,” the authors wrote.