Dr. Berg later focused specifically on 2 a.m., explaining how the body’s circadian rhythm is meant to work. Normally, cortisol is lowest around 2 a.m. and peaks around 8 a.m. In his case, the cycle was reversed—he felt alert at night and exhausted in the morning.

Long-term sleep deprivation, he noted, has been linked to serious conditions including heart disease, dementia, and diabetes.

Ways to lower cortisol at night

Dr. Berg says there are strategies that may help reduce cortisol levels while sleeping and prevent those early-morning awakenings. One of the most important, he says, is magnesium.