New research has revealed that cortisol levels, often referred to as the “stress hormone,” begin rising hours before waking up, as the body prepares for the day ahead. This finding challenges the previous understanding that cortisol levels only spike upon waking.

The study, led by researchers at the University of Bristol in the UK, shows that the body’s natural rhythm triggers an increase in cortisol levels even before a person is fully awake. This process is part of the body’s preparation for the physical and mental demands of the day.

Cortisol levels fluctuate throughout the day in accordance with a person’s 24-hour cycle, typically increasing in response to stress. The new findings suggest that waking up may not be as “stressful” as previously thought, as cortisol levels are already elevated in anticipation of daily activities.

This research provides a deeper understanding of how the body functions during sleep and the early morning hours, contributing to the growing field of studies focused on the body’s natural stress responses and circadian rhythms.