“Cortisol” has become a buzz word among the sleep deprived, the overweight and the WebMD user. The adrenal glands produce this hormone as a response to stress. If your stress is immediate, as in “that car just cut me off and I almost died” or as it was for our ancestors, “a saber tooth tiger is chasing me,” cortisol functions as one of our “fight or flight” hormones.
Its job is to ensure you have plenty of food ready to fuel your actions, whether that is swerving to the other lane or outrunning a beast. But if your stress is long term, as in “my boss is insufferable” or as it was for our ancestors, “winter is coming,” cortisol functions to prepare us for a famine. Now, its job is to ensure there’s plenty of fuel available for the next few months because your stress is unlikely to go away anytime soon.
In both acute and chronic stress, cortisol counteracts insulin, whose job is to decrease blood sugar. However, when in a fight or flight situation, the cortisol stops this decrease. It recognizes the need for readily available sugar in the blood for fast action fuel. Insulin decreases blood sugar in part by having the muscles store it as intermediate fuel, glycogen. But when the stress is chronic, cortisol prevents insulin from working, and the sugar in the blood is stored as long term fuel, fat. This is what is needed to survive the continued stress of impending famine.
Our ancestors went to sleep when the sun went down and sunlight essentially controlled their cortisol production. Seasonal variations in the amount of sunlight per day would inform us about the availability of food. When days were long, it was summer and there was plenty of food. But summer also meant winter was right around the corner and there would be less food available. This lack of food was the only “long term stress” our ancestors had to deal with.
There were no thoughts of, “I think I’m going to lose my job.” Or “I’m unhappy in my marriage.” And there definitely was no one stressed with “I’m being crushed by the debt of my student loans.” Their stress was simply, “there’s going to be less food tomorrow than there is today.” However, that was enough to turn on cortisol production to start storing fat. Long days of summer meant that winter was coming, so we better pack on the pounds now so we can survive until spring.
Today, with the invention of the lightbulb and all of the fancy modern technology, we don’t go to sleep when the sun goes down. Once the sunlight and sleep patterns are uncoupled, cortisol production is controlled by sleep alone. Now, even during the short days of winter, the lights are on for at least 12 hours, and we stay awake late into the evening. The lightbulb has allowed us to override the environmental cues of what time of year it is and we are living in an endless summer.
As a result, this means that year-round, our body is under the seasonal stress of “winter is coming.” With that stress comes cortisol to “protect” from famine. This is caused by insulin resistance to allow the body to store more fat and enable a person to survive until spring. But since we are preparing for a winter famine that never comes, we have developed alarming rates of insulin resistance and obesity, as well as, all of the chronic health conditions that they cause.
What to Do?
The best way to truly regulate your cortisol levels is to sleep. In light of this evolutionary perspective of sleep and cortisol, it is clear that the focus is not simply the total number of hours a person sleeps or the hours slept before midnight. Instead, place the priority on how soon a person goes to sleep after the sun goes down.
We must recouple our sleep patterns to the seasonal rhythms of the sun in order to break the cycle of the endless summer and to reverse the harmful effects of year-round cortisol production. Our biological clock needs 9.5 hours of sleep a night for 7 months a year. This sometimes means getting to bed by 9 pm, which is a huge shift for most of us. But as our favorite sleep author T.S. Wiley likes to remind us, “Will this affect your social life? Yes, but so will obesity and cancer.”
If interested in looking closer at how cortisol affects your health, contact our office for a salivary cortisol panel. Feel free to also schedule an appointment to discuss your specific sleep habits and needs. We want you to sleep well every night.
Written by Lindsea Willon, MS, NTP