Working Out And Sleepless Nights: What's The Connection?

Working out can be great for your health, but it can also lead to insomnia. There are several reasons why you might be unable to sleep after a workout. Firstly, exercise increases the production of stress hormones such as cortisol and adrenaline, which can keep you alert and awake even after the workout. These hormones can remain elevated for up to 48 hours after exhaustive exercise, disrupting your sleep. Additionally, exercise triggers the release of dopamine and serotonin, which are associated with pleasure and reward, further contributing to sleeplessness.

Another factor is the impact of exercise on your body temperature. Working out raises your core body temperature, and it takes time for your body to cool down and prepare for sleep. Therefore, exercising too close to bedtime can interfere with your body's natural cooling process and make it difficult to fall asleep.

Furthermore, electrolyte depletion after working out can also lead to sleep disturbances. Sweating during exercise causes a loss of electrolytes, and if these levels drop too low, it can affect your sleep patterns.

Finally, poor sleep hygiene can also be a contributing factor. This includes habits such as using electronic devices before bed, an uncomfortable sleeping environment, and irregular sleep schedules.

To improve your sleep after workouts, consider having a bedtime ritual, such as reading or listening to calming music. Reducing the intensity of your evening workouts, taking a cold shower, and supplementing with vitamin C can also help.

Hormones and their effects

Hormones are chemical messengers that play a vital role in regulating the body's many processes, systems, and functions. The body needs a range of different hormones to function properly. They're released through the endocrine system, a network of organs and glands located throughout the body.

Hormones are responsible for many bodily functions, including:

• Metabolism and appetite
• Sexual function, drive, and reproduction
• Mood and mental health

The production and function of many hormones in the body are influenced by other body functions, like sleep. Various hormone functions and their release are impacted by sleep or circadian rhythm and vice versa.

• Cortisol: Cortisol is often referred to as the "stress hormone." It is released in response to stress and plays a crucial role in regulating other hormones in the body. Cortisol levels naturally fluctuate throughout the day, typically peaking about 30 minutes after waking up and gradually declining throughout the day. However, intense exercise can cause elevated cortisol levels that remain high at bedtime, disrupting sleep.
• Norepinephrine: Norepinephrine is another hormone that increases during exercise and can remain elevated for up to 48 hours afterward, contributing to post-workout sleep disturbances.
• Melatonin: Melatonin is a hormone that helps regulate the body's sleep-wake cycle. It is produced by the pineal gland and is associated with the body's circadian rhythm. Disrupted sleep can impact melatonin levels and its ability to promote sleep.
• Human Growth Hormone (HGH): HGH plays a vital role in protein production and synthesis, as well as fat metabolism. Sleep impacts the amount and production of HGH in the body. Inadequate sleep can lead to reduced HGH levels, potentially affecting repair and recovery processes.

To regulate hormones and improve sleep quality, it is important to maintain a consistent sleep schedule, manage stress, and create a relaxing sleep environment. Additionally, staying hydrated and proactively cooling down after intense exercise can help lower body temperature, which is essential for restful sleep.

Sleep hygiene

• Set a regular bedtime and adopt a relaxing bedtime routine. Having a consistent sleep schedule helps to regulate your body's internal clock and can improve your sleep quality. Try to go to bed and wake up at the same time every day, even on weekends. Also, develop a calming bedtime routine that helps signal to your body that it's time to wind down, such as reading a book, listening to soothing music, or practising meditation or deep breathing.
• Turn off electronic devices before bed. The blue light emitted by smartphones, computers, and TVs can interfere with the production of melatonin, the hormone that regulates sleep. Try to avoid screens for at least 15 to 30 minutes before bedtime. If you need to use your devices, consider installing blue-light filtering software or wearing blue-light blocking glasses.
• Make sure your bedroom is comfortable and conducive to sleep. Keep your bedroom dark, quiet, and cool. Use blackout curtains, earplugs, or a white noise machine if necessary. Also, make sure your mattress and pillows are comfortable and not too old.
• Prioritize sleep and create a sleep-friendly environment. Avoid stimulating activities close to bedtime, such as intense exercise, watching TV, or engaging in stressful work. Instead, engage in relaxing activities that can help you wind down, such as reading or taking a warm bath. Also, avoid consuming large meals, caffeine, and alcohol close to bedtime, as they can interfere with sleep.
• Limit naps during the day. Long or frequent naps during the day can disrupt your nighttime sleep. If you must nap, try to limit it to 20–30 minutes in the early afternoon.
• If you can't fall asleep, get up and do something relaxing. If you're lying in bed unable to fall asleep, don't force it. Get up and move to another room, and engage in a quiet, relaxing activity until you feel sleepy.
• Exercise during the day. While evening workouts are not inherently bad, they might disrupt your sleep. Try to schedule your workouts earlier in the day if possible. Morning or early afternoon workouts can also help set your body's internal clock and improve your overall sleep quality.
• Consider your workout routine. Evaluate your current workout routine and make adjustments if necessary. You might be overtraining or not allowing enough time for recovery. Consider consulting a physical trainer to assess your routine and make sure it's appropriate for your fitness level.

Core temperature

Core body temperature follows a circadian rhythm, rising and falling across a 24-hour cycle. At the start of the day, body temperature is low and rises steadily throughout the day. As evening approaches, it begins to drop again, signalling to the body that it's time to prepare for sleep.

Exercise increases your core body temperature and can make it difficult for your body to cool down, especially if you are dehydrated. This can lead to sleep disturbances and insomnia.

However, one study found that moderate-intensity exercise performed in the evening does not impair sleep in healthy males, even though it elevates core body temperature.

To optimise your sleep, it is recommended to have a bedroom temperature of around 18.3°C (60-70°F). Taking a warm bath or exercising a few hours before bed can also help to initiate the process of cooling down, improving sleep quality.

Electrolyte depletion

Electrolytes are minerals with an electrical charge that help transmit nerve impulses throughout the body. Electrolyte imbalances, especially in magnesium and potassium, can disrupt sleep quality. Electrolyte supplements can aid sleep by calming the nervous system.

Magnesium is the most researched and publicized electrolyte for sleep. It has relaxative properties that may improve sleep, stemming from changes in neurotransmitter activity. Magnesium blocks N-methyl-d-aspartate (NMDA) receptors in the brain that are sensitive to an excitatory neurotransmitter called glutamate. Less glutamate means less excitatory brain activity that may keep you awake. Magnesium also increases levels of GABA, a calming neurotransmitter. More GABA means more relaxation, potentially better sleep.

Magnesium may also improve sleep by regulating the circadian rhythm, which is the sleep-wake cycle that promotes better sleep. Research suggests that magnesium regulates circadian clocks in plant and animal cells.

Magnesium can also improve sleep by providing hormonal support. A 2012 study found that adults supplementing with 500mg of magnesium per day for eight weeks experienced reduced cortisol (a stress hormone), increased melatonin (a hormone that can improve sleep cycles), and increased renin (a hormone linked to better deep sleep).

Magnesium can also reduce muscle cramps, which may keep you up at night. A 2021 study found that magnesium supplementation significantly reduced nocturnal leg cramps and improved sleep quality in at-risk patients.

Magnesium may also improve sleep by providing anti-depressant effects. Depressive symptoms may cause poor sleep, and poor sleep may cause depressive symptoms. Supplemental magnesium may improve both symptoms of depression and poor sleep.

Low sodium levels have been linked to restlessness and difficulty sleeping. A 1983 study found that three days of sodium restriction increased noradrenaline levels and decreased REM and deep sleep in 10 young men. Low-sodium diets also reduce antidiuretic hormone (ADH) secretion, a hormone that tells our kidneys to retain water. Less ADH can mean more nighttime bathroom visits, potentially disrupting your sleep.

Low potassium levels may also disrupt sleep. A 1991 study found that potassium supplementation increased sleep efficiency (time asleep vs. time in bed) from 89% to 94%. The researchers speculate that potassium may improve the circadian rhythm, leading to more consistent sleep.

Low calcium levels may also disrupt sleep. Calcium-related pathways regulate the duration of sleep. Calcium supplementation might increase the risk of myocardial ischemia. Subnormal levels of vitamin D may lead to atheromatous vascular diseases with accumulation of calcium in the arteries. Vitamin D deficiency can result in insomnia, with poor sleep quality, short sleep duration, and daytime sleepiness.

High-intensity workouts

High-intensity interval training (HIIT) involves short bursts of intense activity alternated with brief recovery periods. This type of training is time-efficient and offers a range of health benefits, including enhanced endurance, strength, and cardiovascular fitness, metabolism, and blood pressure. It can also boost mood and reduce stress.

However, the intensity of HIIT can elevate your heart rate, core temperature, and sweat rate, and stimulate your nervous and endocrine systems. This stimulation can make it challenging to fall asleep or maintain restful sleep. Two hormones that play a significant role in post-workout sleep disturbances are norepinephrine and cortisol, which are released during exercise. Cortisol, in particular, can interfere with your natural sleep cycle if its levels remain elevated for an extended period.

Additionally, dehydration and increased body temperature after an intense workout can further contribute to sleep difficulties. Proper hydration and proactive cooling methods can help mitigate these issues.

If you're experiencing sleep issues after high-intensity workouts, consider the following strategies:

• Maximize your overall fitness level to better handle the acute stress from workouts.
• Minimize lifestyle stress to reduce cortisol levels.
• Ease up on stimulants like caffeine, especially later in the day.
• Proactively cool down after workouts using methods like cold showers, cool clothing, or sleeping in a cooler environment.
• Adjust your workout timing, intensity, or duration to find a balance that suits your sleep needs.

Frequently asked questions