Cortisol's impact on sleep: the stress-hormone connection

Sufficient, good-quality sleep is known to be important when it comes to maintaining good health. However, many factors can disrupt sleep, including high levels of stress. The body’s stress hormone, cortisol, may be elevated in these situations and play a role in this disruption.^[1]

Science of good sleep

Cycles of sleep and wake states are regulated by a number of signals in the body. Several “sleep hormones,” including cortisol and melatonin, play a role in this process and are key to adequate sleep quantity and quality. Other hormones critical to human health are also released during sleep.

Understanding the relationship between these hormones and sleep can provide insights into how sleep affects overall health and longevity.

Melatonin

Melatonin is produced and released in the brain and has direct effects on sleep regulation. It is known as the ‘hormone of darkness’ and is secreted in the absence of light. It helps regulate the timing of sleep, signaling to the body that it is time to go to bed. It rises in the evening and peaks in the early morning.^[2]

Cortisol

Cortisol, in contrast, rises in response to light exposure in the morning. It is important for dealing with stressors on the body^[3]. Levels are high in the morning and low at night, following a circadian rhythm that helps regulate the sleep-wake cycle.

Research shows that a healthy cortisol rhythm, where levels drop significantly from sleep onset to awakening, is associated with better subjective sleep quality, especially in older adults.^[4]

Growth hormone

Growth hormone is also released in a cyclical fashion and is mostly secreted during deep sleep. It helps to maintain body structure and plays a role in muscle repair. Too little sleep may result in less growth hormone and impaired muscle repair.^[5]

As we age, we experience a decline in growth hormone, which is paralleled by a decrease in deep sleep and an increase in evening cortisol levels. This disruption in the sleep-wake cycle and the hypothalamic-pituitary-adrenal (HPA) axis may contribute to the aging process.

Ghrelin and leptin

Ghrelin and leptin are hormones that promote hunger and satiety, respectively. Quantity of sleep has been shown to affect levels of these hormones. Imbalances may lead to increases in hunger and risk of weight gain.^[6]

About cortisol

Cortisol is made from cholesterol and has a variety of effects on the body. It is able to affect almost all organ systems. It is not only involved in the stress response but also in regulating metabolism, inflammation, and immunity.^[7]

Cortisol is made from cholesterol and has a variety of effects in the body. It can affect almost all organ systems and is involved in regulating metabolism, inflammation, and immunity. Sustained high cortisol levels and cortisol dysregulation are associated with several health concerns, in addition to its negative impact on sleep.^[8]

Cortisol and sleep

Research studies have revealed a relationship between cortisol levels, sleep cycles, and sleep quality. For example, one study explored the relationship between stress, sleep, and cortisol levels. Researchers tracked healthy participants over eight days and found that greater stress levels were associated with shorter sleep and higher waking cortisol levels. These findings revealed the potential impact of stress on sleep and cortisol levels.^[9]

Disruptions in sleep have also been shown to be associated with a rise in cortisol levels and affect the circadian release pattern of this hormone. ^[10]In a study of type 2 diabetics, for example, sleep problems were associated with disturbances in cortisol responses to stress and changes in cortisol levels. Those who had greater sleep problems had higher levels of cortisol throughout the course of the day.^[11]

Longevity hacks for better sleep

Given the importance of sleep for health and longevity, a focus on sufficient quantity and quality of sleep is important. There are several possible ways to improve sleep that take into account the action of hormones and how sleep is regulated.

Increase natural daylight exposure

Living in urban environments may lead to altered light exposure, including less natural light during the daytime and less darkness during the night. Given this, expert recommendations have been developed for optimal exposure to light.^[12] These include exposure to daylight whenever possible and the additional use of electric lighting when needed.

At night, exposure to light should be kept at a minimum, with the sleep environment being kept as dark as possible.^[13]

Exercise

Physical activity has been shown to be associated with better sleep quality. ^[14]Those who are more active generally sleep longer and are able to fall asleep faster. These results have been found both in children and adults.^[15]

Cognitive behavioral therapy

Stress management using cognitive behavioral therapy is another strategy to improve sleep. This approach involves changing beliefs and unrealistic expectations related to sleep^[16]. A study in older adults, for example, showed that an eight-week mindfulness-based cognitive therapy program resulted in improvement in sleep problems, as well as less anxiety and fewer depressive symptoms.^[17]

Consume a healthy diet

Previous research suggests that eating the right quantity and quality of food containing all the essential nutrients may be important for good sleep. This includes consuming a diet with enough of the macronutrients carbohydrates, protein, and fat, as well as enough of key nutrients such as omega-3 fatty acids. Limiting highly processed food may also be important.^[19] However, more studies are needed to understand the relationship between nutrition and sleep.^[18]

Wrapping up

Understanding the intricate relationship between cortisol, sleep, and longevity highlights the importance of maintaining good sleep hygiene as part of a healthy lifestyle.

Managing stress effectively, ensuring sufficient and high-quality sleep, and adopting healthy lifestyle habits such as regular exercise, a balanced diet, and proper light exposure can help maintain a healthy cortisol rhythm, support better sleep, and enhance your overall well-being.

Incorporating these strategies into your daily routine not only improves sleep but may also extend your healthy years, enabling you to live a longer, more vibrant life.