When you don’t get enough sleep, your hormones undergo significant changes that affect many aspects of your body and health. Hormones are chemical messengers that regulate processes like metabolism, appetite, stress response, growth, and reproduction. Sleep deprivation disrupts the balance of these hormones, leading to effects such as increased hunger, weight gain, difficulty losing weight, and impaired physical performance, including activities like running.
One of the most affected hormones is **cortisol**, often called the stress hormone. Normally, cortisol levels follow a daily rhythm, peaking in the morning to help you wake up and gradually decreasing throughout the day. When you don’t sleep enough, cortisol levels become elevated and stay high for longer periods. This chronic elevation can increase stress, promote fat storage (especially around the belly), and interfere with your body’s ability to regulate blood sugar. High cortisol also makes it harder to lose weight because it encourages your body to hold onto fat and break down muscle tissue, which slows metabolism[1][5][11].
Another key hormone affected by lack of sleep is **ghrelin**, which stimulates appetite. When you are sleep deprived, ghrelin levels rise, making you feel hungrier than usual. At the same time, levels of **leptin**, the hormone that signals fullness, decrease. This imbalance causes you to eat more, especially craving high-calorie, sugary, and fatty foods. This hormonal shift can lead to overeating and weight gain, making it difficult to maintain or lose weight despite efforts like running or other exercise[5][7][9].
Sleep deprivation also reduces the secretion of **growth hormone**, which is important for muscle repair, fat metabolism, and overall recovery. Growth hormone is mostly released during deep sleep stages, so missing out on quality sleep means your body produces less of it. This reduction can impair muscle growth and recovery, reduce energy levels, and slow down metabolism. For people who run or engage in physical activity, this means slower recovery times and less efficient fat burning, which can hinder weight loss goals[5][9][11].
**Insulin**, the hormone that controls blood sugar, is also affected by poor sleep. Sleep deprivation can cause insulin resistance, where your body’s cells don’t respond properly to insulin. This leads to higher blood sugar levels and increases the risk of developing type 2 diabetes. Insulin resistance also makes it easier to gain weight and harder to lose it because your body stores more fat and struggles to use glucose for energy efficiently[1][5].
Sex hormones such as **testosterone** and **estrogen** are influenced by sleep as well. Testosterone, important for muscle mass, energy, and mood, drops significantly with insufficient sleep. Even one night of poor sleep can reduce testosterone levels by 10-15%. Lower testosterone means less muscle preservation and slower metabolism, which can contribute to weight gain and fatigue. For women, disrupted sleep can affect estrogen and progesterone balance, impacting reproductive health and overall hormonal stability[1][9][11].
The hormone **melatonin**, which regulates your sleep-wake cycle, is also disrupted by poor sleep habits. Melatonin helps you fall asleep and stay asleep. When your sleep is fragmented or shortened, melatonin production can be thrown off, making it even harder to get restful sleep. This creates a vicious cycle where poor sleep leads to hormonal imbalances, which then further impair sleep quality[3].
All these hormonal changes combine to create a challenging environment for maintaining a healthy weight. When you’re sleep deprived, your body is more likely to crave unhealthy foods, store fat, and lose muscle mass. This makes activities like running feel harder and less effective for weight control. Even if you are running regularly, the hormonal disruptions caused by lack of sleep can slow down your progress in losing weight or maintaining a healthy weight.
In addition to weight and metabolism, these hormonal shifts affect mood, energy, and cognitive function. Elevated cortisol and disrupted sex hormones can lead to irritability, anxiety, and difficulty concentrating. This can reduce motivation to exercise or maintain healthy eating habits, further compounding the negative effects on weight and overall health.
Understanding how hormones change when you don’t sleep enough highlights the importance of prioritizing good sleep hygiene. Getting enough quality sleep supports balanced hormone levels, which in turn helps regulate appetite, metabolism, stress, and physical performance. This balance is essential for anyone looking to lose weight, maintain a healthy weight, or improve their running and fitness outcomes.
Sources
https://ubiehealth.com/doctors-note/sleep-deprivation-hormonal-health
https://lamclinic.com/blog/metabolism-sleep-and-stress/
https://bodysymmetrymd.com/improve-sleep-by-balancing-your-hormones/
https://www.lainierowell.com/ewgtranscripts
https://en.wikipedia.org/wiki/Sleep_deprivation
https://sleepmattersllc.com/blog/your-sleep-is-sabotaging-your-metabolism-heres-how/
https://pmc.ncbi.nlm.nih.gov/articles/PMC12610528/
