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Why Do Hot Tubs and Saunas Make You Sleepy?

By Amelia Willson | 4 Minute Read

Is there anything better than the steamy feel of a hot tub or sauna after a long day or workout? Hot tubs and saunas make you feel fantastic. You may have noticed they make you feel sleepy, too.

Why do hot tubs and saunas make you sleepy? We explore.

5 reasons why hot tubs and saunas make you tired

When it comes to feeling tired after soaking in a hot tub or sauna, there’s actually a variety of factors at work. Learn more about each one below.

1. They’re relaxing.

Unless you’re absolutely exhausted, you typically need to feel relaxed to fall asleep. Spend 15 minutes in a hot tub or sauna and you’re bound to feel relaxed.

The heat releases endorphins, those happy hormones that make you feel good. Endorphins can help clear your mind of any emotional or mental stress you’re carrying around, enabling you to let things go and relax.

A hot tub or sauna relaxes you physically, too, by relieving achy joints and muscles. If you’re in a hot tub, the buoyancy of the water helps your muscles relax and decompress. Joint pain and discomfort can disrupt the quality of your sleep, as your body has to shift positions to relax enough to sleep. If your body feels comfortable, you’re more likely to feel relaxed and sleepy.

To improve the relaxation effect of your hot tub or sauna, combine it with aromatherapy. Lavender, sandalwood, and chamomile essential oils all have calming effects on the mind and body. You might add a few drops to the hot tub directly or dilute essential oils with the water you use to splash over the sauna rocks.

2. They facilitate thermoregulation.

One of the biggest factors behind the soporific effect of hot tubs and saunas is the way they aid your body’s natural thermoregulation process. Throughout the day, your core body temperature naturally rises and falls in accordance with your sleep-wake cycle. It rises throughout the day, reaching its peak in the early evening, at which point it begins to fall. When this nighttime temperature dip happens, your brain sees it as a signal that it’s time to fall asleep.

When you enter a hot tub or sauna, your body’s core temperature rises. When you get out, it begins to drop as the hot water and sweat evaporates from your skin. This cooldown mimics the same cooldown your body naturally experiences at night when it’s time to start getting sleepy.

This is why soaking in a hot tub or sauna as part of your bedtime routine can make it easier for you to fall asleep at night. Research has found that a daily warm bath can shorten sleep onset. However, it can take about 60 to 90 minutes for your body temperature to stabilize after a 15 minute soak, so you should time your hot tub time accordingly. Use the sauna right before bed, and you might be too hot to fall asleep comfortably.

3. They improve blood flow and circulation.

When you’re under stress, your blood vessels constrict. This makes it more difficult for them to circulate throughout your body, so your body has to work harder to allow them to do so. Many of us are living in a constant state of stress, so our bodies are already working harder to circulate the blood. When you throw in intense physical exercise (which often occurs before a sauna or hot tub session) your muscles have to work even harder—at a time when they’re already exhausted from working out.

Get into a hot tub or sauna, however, and the warm water or steam begins dilating your blood vessels. This allows your blood to circulate freely and perform its important job of removing toxins from your tired muscles and helping them heal.

This process is important for restoring your body from the stresses of the day, but it takes its own toll, too. Rebuilding your muscles takes work, so it’s natural for your body to feel tired afterwards.

4. They can be dehydrating.

The time you spend in a hot tub or sauna increases your risk of dehydration. Your body is working against the heat of the water to maintain your core body temperature, while it’s circulating your blood to repair and restore your muscles. You can also lose additional fluids through sweat.

One of the side effects of dehydration is exhaustion, explaining yet another way saunas and hot tubs make you feel sleepy. To ensure you stay hydrated, make sure to drink plenty of water both before and after your time in the sauna or hot tub.

5. The time of day has something to do with it.

Finally, there’s the obvious matter of time. It’s common for many people to enjoy a sauna or soak at the end of the day, or after a strenuous workout. In either of these scenarios you’re simply more likely to be sleepy.

Working out is physically exhausting. It tires out your muscles, which is why a regular exercise routine can be so good for sleep—even if you do it early in the day.

If you get into a sauna or hot tub at the end of the day, you’re also going to be more tired. You may have had a busy day working, running errands, or getting together with friends and family. Plus, the end of the day corresponds with the evening—that time of day our brains naturally start getting sleepy.

Embrace sleepiness

There you have it: five ways hot tubs and saunas make you sleepy. Since they do such a great job making you sleepy, consider working your hot tub or sauna time into a later part of the day. You’ll be more relaxed, and you’ll enjoy better sleep.

If you’re interested in learning more about the relationship between heat and sleep, check out the articles below:

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