by Lindsea Willon, MS, NTP
“Cortisol” has become a buzz word among the sleep deprived, the overweight and the WebMD user. Cortisol is a hormone produced by the adrenal glands in 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 make sure you have plenty of readily available food to fuel your action, whether that action 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. Its job is now to make sure you have 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. But when we have a fight or flight situation, cortisol stops the decrease because we need all the sugar in the blood we can get as our readily available fuel for fast action. 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 so the sugar in the blood gets stored as long term fuel, fat, which is what we need to survive the continued stress of impending famine.
Our ancestors went to sleep when the sun went down and their cortisol production was essentially controlled by sunlight. 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 means winter is right around the corner, so the long days of summer also meant that soon there would be less food available. This lack of food was the only “long term stress” our ancestors had to deal with. No “I think I’m going to lose my job,” “I’m unhappy in my marriage,” or “I’m being crushed by the debt of my student loans.” Just, “there’s going to be less food tomorrow than there is today.” But 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.
But now with all of our fancy modern technology like the lightbulb, 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 as if it were summer. 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. This means that year-round our body is under the seasonal stress of “winter is coming.” And with that stress comes cortisol to “protect” you from famine by causing insulin resistance to allow you to store more fat so you can 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 and all of the chronic health conditions that they cause.
The best way to truly regulate your cortisol levels is to sleep. In light of this evolutionary perspective of sleep and cortisol, it becomes clear that it is not simply the total number of hours you sleep, or even the hours you sleep before midnight that matters, but rather how soon after the sun goes down you go to sleep. 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 you are interested in taking a closer look at how cortisol is affecting your health, ask our office for a salivary cortisol panel and make an appointment to talk about setting up healthy sleep habits, tools to reduce your blue light exposure in the evening and supplemental adrenal support. We want you to sleep well every night.