Human beings sleep for approximately one-third of their entire lifetime. It’s one of the key elements to better quality of life, body optimization, and hormonal balance. Several hormones are affected by sleep, including cortisol, leptin, ghrelin, testosterone, and melatonin. These hormones, directly influence metabolism, body composition, insulin sensitivity, and appetite. We’re going to talk more about how sleep affects your body from metabolism, hormones, muscle mass, body fat, and sex drive, and how you can optimize sleep quality to improve hormonal balance.  

How Does Sleep Loss Affect Obesity (Leptin And Ghrelin) 

Compared to a few decades ago, on average, we all get far less sleep. Accumulating evidence from both epidemiological studies and laboratory studies indicates that chronic sleep loss may have severe adverse effects leading to weight gain, obesity, as well as metabolic and endocrine alterations leading to decreased insulin sensitivity, increased cortisol levels, increased levels of ghrelin, decreased levels of leptin and increased hunger and appetite. 

Studies indicate that leptin, a satiety hormone secreted by the adipocytes, and ghrelin, a hunger hormone released primarily from stomach cells, are both partly dependent upon sleep timing, duration, and quality. The release of human growth hormone and cortisol are also dependent upon sleep and sleep quality.

Increased caloric intake and decreased physical activity are two evident reasons for the increased prevalence of obesity, however sleep is also another contributing factor. Over the past few decades sleep has decreased, while obesity has increased.  A poll conducted by the National Sleep Foundation in 2008, revealed that sleep on average was 6 hours 40 minutes during weekdays and 7 hours 25 minutes during the weekend [R]. In contrast, in 1960, the average sleep duration was 8.5 hours [R].

Evidently, there is a direct correlation with obesity and less sleep. Cross-sectional and prospective studies have found positive associations with the risk of obesity greatly increased with sleep durations under six hours. Leptin levels are lowest when in a state of sleep debt, signaling to the brain an unnecessary need for caloric intake. A study confirmed that leptin levels significantly decreased, by 18% with shorter sleep durations, while ghrelin levels significantly increased by 28% after two nights of 4 hours of sleep each night [R]. Therefore, less sleep can increase hunger and cause you to increase caloric intake. If you find yourself rummaging through the fridge for a midnight snack, because you can’t sleep, it’s due to a hormonal signal of ghrelin and leptin.

It’s proven that decreased sleep duration and poor sleep quality is directly linked to obesity and increased body fat. Sleep is a restorative process of the brain, and without getting enough quality sleep you make poor decisions, including decisions about when what, and how much you eat [R]

To date, there have been over 50 epidemiological studies that have examined the association between sleep duration and obesity. The majority found a direct relationship between shorter sleep duration and increased body fat.

How Does Sleep Loss Affect Metabolism (Human Growth Hormone (hGH) and Insulin)

Human growth hormone is produced by the pea sized pituitary gland – located at the base of the brain. hGH helps maintain your body structure and metabolism, having an impact on maintaining normal blood glucose levels. hGH is intermittently released during the day, however most prevalent while you sleep.

Several hormones are involved with sleep and circadian rhythmicity. Human growth hormone is increased during sleep and peak after you fall asleep [R].

Growth hormone is intermittently secreted while you sleep and increases significantly during slow-wave sleep (SWS) as compared with stages 1 and 2 of REM [R]. Thyroid stimulating hormone concentrations increase and reach their max in the middle of the night and minimum in the afternoon [R].

In adults, the most human growth hormone is secreted shortly after sleep onset, or when you fall asleep. Approximately 70% of the goth hormone coincides with SWS [R].

hGH impacts metabolism primarily by increasing the production of insulin-like growth factor-1 (IGF-1) and its effect on cells in your body. IGF-1 acts similarly to insulin and manages the effects of hGH in your body, promoting glucose lowering effects.

Insulin is the main hormone produced to help regulate blood glucose levels when they get too high, and glucagon is the main hormone produced when glucose levels get too low.

When sleep onset is delayed, or sleep quality is deterred, hGH levels can decline. Lower hGH levels have a direct impact on metabolism, releasing less IGF-1 and affecting glucose levels [R].

How Does Sleep Affect Stress (Cortisol)

Cortisol levels, your body’s primary stress hormone also exhibits circadian rhythmicity. Cortisol levels rapidly rise in the middle of the night and peaks in the morning. Cortisol is released in a pulsatile manner, throughout the 24-hour day, and decreased during SWS [R].

Poor sleep quality and sleep duration can largely contribute to stress and metabolism, through the hypothalamic–pituitary–adrenal (HPA) axis activation. When sleep deprivation occurs, maladaptive changes take place in the HPA axis leading to neuroendocrine dysregulation. Excess of glucocorticoids increase glucose and insulin and decrease adiponectin levels. Adiponectin is a hormone your adipose (fat) tissue releases that helps with insulin sensitivity and inflammation.

Studies report that those who are affected by sleep disorders, such as insomnia or obstructed sleep apnea, have elevated cortisol levels [R]. When sleep deprivation occurs, cortisol levels will increase during the day, in an effort to maintain wakefulness.  

How Does Sleep Affect Muscle Gain (Testosterone)

The majority of daily testosterone release occurs during sleep. Sleep fragmentation, disruption, or obstruction are directly correlated with reduced testosterone levels [R].

Testosterone is a vital male and female hormone, contributing to growth, body composition, muscle size and strength, as well as sex drive. Signals from the brain to the pituitary gland, the same gland that controls release of human growth hormone and cortisol, controls the production of testosterone in men. In women testosterone is produced in the ovaries and adrenal gland. It’s one of several androgens (male hormones) in females.

Symptoms of low testosterone levels in men which can occur from poor sleep or sleep deprivation include

• Loss of muscle mass
• Increased body fat gain
• Low libido
• Irritability
• Poor concentration
• Chronic fatigue

Symptoms of low testosterone levels in women which can occur from poor sleep or sleep deprivation include 

• Decreased sex drive
• Poor musculoskeletal health
• Depression and mood swings
• Muscle loss
• Mental fogginess
• Physical fatigue

Without adequate amounts of sleep and sleep quality, these symptoms can occur, which will disrupt athletic performance, as well as overall health and wellness aspirations.

How Does Sleep Affect Hormones: Takeaway

Several hormones which regulate your metabolism, stress, and body composition are affected when sleep quality and duration are altered [R].

Sleep, metabolism, and stress, interact in a bidirectional fashion sharing multiple pathways increasing the prevalence of chronic disease such as obesity and diabetes.

If you are experiencing weight loss plateau, if you have gained body fat, lost muscle mass, have increased stress levels, or find your eating patterns disproportionate, this could be due to a loss of sleep, disruption in sleep pattern, or sleep deprivation. Aiming for at least 7-8 hours of high-quality restful sleep per night, is paramount, for metabolism, body composition, and better quality of life. If you find yourself experiencing these symptoms, we recommend a potent clinically dosed sleep supplement such as Swolverine’s ZMT.

Looking for the best sleep supplement to help you better quality sleep?

Walter Hinchman

Walter Hinchman is the Founder and CEO of Swolverine. He is a NESTA and ACE certified trainer and holds a Masters Degree in Business and in Finance and Economics.