Cortisol and Sleep- the Adrenal Gland Fatigue Connection

By on October 18, 2009

We all know that we feel better when we are getting enough sleep, and every health pundit tells us that getting enough sleep is extremely important to your health. But when you sleep are you getting all of the benefit that you COULD be?

We hear a lot about getting enough sleep, but rarely do we hear about the TIMING of your sleep and the importance of the adrenal gland fatigue hormone called cortisol and sleep. And the TIMING is AT LEAST as important as getting enough sleep.

Humans evolved as diurnal animals. That means that, as a species, we evolved to sleep at night as opposed to the daytime. For thousands of years, we had no light except firelight after dark and therefore we slept when it became dark. With the advent of the electric light, we have learned that we can manipulate this rhythm and stay up all night if we desire. But our manipulation of the environment, in this particular case, is to our detriment of the cortisol and sleep rhythms and contributes to Adrenal Gland Fatigue.

The adrenal glands, a pair of small glands that sit on top of each kidney, produce the hormone cortisol, among other hormones. Cortisol is one of the main hormones responsible for the stress response in our bodies. It goes up when we are stressed and ideally it returns to normal when stress is reduced. Some people are stressed so much that their cortisol level is continually high. Others have had so much stress in their life that their adrenals are unable to produce enough cortisol to remain at normal levels even when the stress is removed. These people have chronically low cortisol levels – not a good state to be in.

Interestingly, cortisol has a daily rhythm of ups and downs. Levels are highest at about 6 am and lowest around 10:00 pm. This gives us the energy we need to function throughout the day and allows our bodies to rest and repair during the night as we sleep. This rhythm is MOST effective if we go to bed around 10:00 to 10:30 PM and wake up around 6:00 to 6:30 in the morning. Humans are designed to these cortisol and sleep cycles based on our exposures to light and dark from thousands of years of evolution. These levels are OUTSIDE OF OUR CONTROL and we cannot change them based on when we work and when we sleep. People who consistently work at night and sleep during the day do NOT reset this rhythm, they go AGAINST this rhythm and it will eventually catch up with them.

In fact, workers who do shift work have higher levels of certain diseases- notably breast cancer and cardiovascular disease, than people who work daytime hours. Any amount of time that you go to sleep after 10:30 PM, your body will perceive as stress, disrupting your cortisol and sleep cycles and contributing to adrenal gland fatigue. To make matters worse, the late night DROP in cortisol levels that occur when you go to bed in an unstressed state around 10 pm is what triggers the release of Human Growth Hormone. Human Growth Hormone (HGH) is directly related to the regeneration and repair of the body. It is SO effective that a relationship has been observed between the vitality of elderly adults and their HGH levels.

There is a whole industry out there trying to make effective HGH supplements so that people can feel more vital and have more energy. Most of these supplements have been largely ineffective and the studies that have shown these remarkable effects from HGH have mostly been done with injections. But YOU can boost the levels of HGH in your body and reap the benefits that so many people are trying to get in supplement form. Just go to bed between 10 and 10:30 PM and get about 8 hours of sleep and you will MAXIMIZE the amount of HGH that you produce, contribute to a positive cortisol and sleep balance and ward off Adrenal Gland Fatigue.

The hours between 10 pm to 2 am are PRIME hours for rest and repair where the highest amount of HGH is produced. You CAN NOT make this up by sleeping in later. Your body ONLY produces these hormones during these particular hours. If you miss it, it’s gone forever! Cortisol and sleep cycles are also responsible for Immune System Health. When cortisol levels are too high or too low, the immune system can’t work at its best. By going to bed late, you are making yourself chronically susceptible to colds, flu, infections and even cancer if your stress levels compromise your immune system bad enough for long enough.

Coming in second only to dietary changes, sleep is the most effective lifestyle change that you can make. If you get to bed later than 10:30 regularly, you can make PROFOUND changes in your health just by getting your cortisol and sleep cycles back in balance and improving your adrenal gland fatigue.

Adrenal Gland Fatigue Resources


  • Test Your Adrenal Glands Right in Your Own Home
  • Sleep Supplements– Get a good night’s sleep with Melatonin
  • About Kerri Knox, RN

    The author is a Registered Nurse and Functional Medicine Practitioner. With 20 years of experience in health care, she has the unique perspective of being solidly grounded in both Conventional Medicine and Alternative Medicine. She can help you to to find and repair the underlying causes of chronic illness, while empowering you to take charge of your own health. She is the owner and author of this blog and website.

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