Health: about body temperature and sleep quality!

A good night’s sleep is extremely important for our physical and mental health. It’s no wonder, then, that many people want to know how they can improve their sleep quality. Your body temperature is one of the major factors that affects your sleep quality. In this blog, we’ll explain how the temperature of your surroundings and your body affects your sleep quality.

How important is temperature to sleep quality?

The temperature of your environment and of your body itself plays an important role when it comes to sleep quality. So many people can also easily gain here when it comes to their sleep.

Most people are unaware of what temperature does to their sleep. For example, how warm should it be? And what blankets are best to use or when do you sleep with the window open or closed? These are all, sometimes crucial, factors that can improve your sleep quality.

The ideal sleeping environment

Your sleeping environment is the biggest factor where you can easily make gains in terms of temperature. Of course it should be comfortable, but what temperature your bedroom is is something that is often not thought about.

So what is the ideal bedroom temperature? Research shows that a constant ambient temperature of 18°C is best. At that temperature, your body gets the best quality of sleep possible.

There are a number of factors in your control to create the ideal sleep environment:

• Keep your bedroom adequately cool in the summer. As mentioned, a room temperature of around 18 degrees is ideal.
• Use the right blankets or duvets. If your bedroom is the right temperature, duvets that are too thick or too thin can disrupt your sleep, making you too hot or too cold. Bedding textiles are also best adapted to the season.
• Provide a dark room while sleeping. The hormone melatonin helps you fall asleep easily and is released when it gets dark. Bright light, especially blue (LED) light, interferes with its release.
• Avoid looking at screens—such as phones, tablets, and televisions—right before bed. That’s because they emit a lot of blue light. On certain devices and/or apps, you can enable a night filter that emits more red light.

Which blankets or duvets are best to use?

The most important thing, of course, is that you have blankets or duvets that you feel comfortable with. This is mainly a matter of personal preference—such as whether you prefer a heavy or light blanket, or a thin or thick duvet. Make sure your blanket or duvet isn’t too warm or too cold for you. Both of these situations will wake you up and disrupt your sleep cycle.

Best is a blanket made of natural materials such as cotton or wool, for example. These materials are strong in heat and moisture regulation, and naturally ventilate very well. Do you like to be warm? Then you can also choose a down comforter. With synthetic materials, your body often has a slightly harder time regulating its own temperature so they can feel too warm more quickly. That doesn’t have to be a disadvantage, if you get cold faster of course. There are synthetic variants, such as ThinsulateTM, which imitate natural fibers. The advantage is that synthetic duvets are easier to wash yourself.

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Can you sleep with the window open?

Many people like to sleep with their window open—or at least slightly ajar. Is this good for the quality of your sleep? The answer is yes, as long as you time it right. Good ventilation in the bedroom is very important, and the best way to achieve that is indeed by keeping your windows wide open. But it’s important to close them again afterward, especially when it’s cold outside. This allows your bedroom to warm back up to 17 to 18 degrees. During the warmer summer months, it’s different—close them when your bedroom threatens to get too hot.

Especially during cold spells and particularly in the winter, it’s best to keep your windows completely closed during the day. And if you’d still like to open the window or leave it slightly ajar at night, it’s best to do so just before you get into bed. Your bedroom will be at the right temperature, and your bedding and mattress will feel comfortable when you get into bed. In the morning, after waking up, it’s best to air out the room briefly and thoroughly—for half an hour to an hour—and then close the windows again. The temperature will rise again. And because warmer air can hold moisture better, you’re less likely to have damp sheets or condensation on the windows.

Why is temperature so important?

Sleep quality and body temperature are closely linked. The biological clock controls our body’s heat balance and ticks according to the circadian rhythm. This greatly determines our sleep and wake rhythm.

This automatic and independent rhythm repeats itself day after day, causing our core body temperature to drop at night and rise again during the day. People who have irregular work schedules, travel frequently between continents, or often work night shifts are highly sensitive to the often abrupt adjustments to their internal biological clock. As a result, their sleep is severely disrupted. This applies to men, women, young people, and older adults alike. In short, we all suffer from this.

Prolonged poor sleep has dire consequences for your health. The immune system weakens so you can get sick faster. The risk of cardiovascular disease also greatly increases, according to several researchers. In these cases, always contact a doctor or sleep expert for more advice.

Body temperature or skin temperature

In body temperature, we distinguish between core temperature and skin temperature. Core temperature is vital to us because the functioning of our organs, for example, depends on it. The body makes every effort not to have excessive temperature differences.

A degree more or less—it seems so trivial. But to put it simply, a core temperature above 38°C means you have a fever and are clearly not feeling well. If your body temperature drops below 35°C, we call it hypothermia. There’s only a difference of a few degrees between these two situations, but this can be life-threatening.

Your body reacts using an important tool: the skin. For example, when you get cold, you start to shiver, which warms you up. If your body needs to lower its temperature, the ingenious process of perspiration kicks in, allowing your body to cool down its core temperature.

Core body temperature rises slightly during the day and drops again at night, regardless of whether you are asleep or awake at that time. However, the differences are less pronounced when measuring core body temperature compared to skin temperature. Temperature readings taken at the skin’s surface are significantly higher at various times throughout the day. These changes in body heat are very important and influence our sleep-wake cycle.

When we go to sleep, our core body temperature drops by about one degree. This allows us to fall asleep easily. Around 4 a.m., this core temperature is lowest. The temperature then rises again in the morning when we wake up. During the late afternoon, this temperature reaches its peak.

Our skin temperature rises when we sleep and evens out with our core temperature. You’ll notice this if you go to bed later than your partner, for example. It’ll feel as if you’re lying next to a space heater.

It’s clear that body temperature plays an important role in how easily we fall asleep, how well we sleep through the night, and how easily we wake up. That’s why it’s important to sleep in an environment where this natural process—called thermoregulation—can take place unimpeded. So, not too cold or too hot!

The biological clock and body temperature

Throughout the day and night, our body temperature fluctuates. These temperature fluctuations follow a natural rhythm. This internal biological clock, just like the standard clock, is divided into 24-hour periods. This is also known as the circadian rhythm.

Some of these processes that are automatically activated in our body by the various alarm clocks in the biological clock include: body temperature, selected hormone release and slowing down or speeding up our metabolism.

Heat and Your Sleep Stages

The relationship between temperature and sleep quality goes beyond simply “having trouble falling asleep.” When the ambient temperature is too high, the structure of your sleep changes. Research shows that exposure to heat during the night leads to more time spent awake, as well as less deep sleep and less REM sleep.

That sounds technical, but the practical implication is very clear. Deep sleep (N-REM 3) is the phase during which your body recovers. Your muscles regenerate, your immune system is replenished, and memory information is stored. Meanwhile, REM sleep (or paradoxical sleep) is the phase that helps you process emotions and ensures your ability to concentrate the next day. If heat shortens both phases, you may be getting enough sleep in terms of hours (quantity), but you’ll get less recovery per hour (quality).

The reason: thermoregulation. To reach deep sleep stages, your core body temperature must drop sufficiently. An environment that’s too warm blocks that process or interrupts it repeatedly. In other words, you have trouble falling asleep, and your body expends energy to cool down.

Another factor that is often underestimated is humidity. Dry heat is uncomfortable, but humid heat increases the thermal stress even more. You sweat, and that sweat evaporates more slowly because the air around you is already quite humid. As a result, your body cools down less efficiently, and the impact on your sleep stages is greater than with dry heat at the same temperature.

Would you like to know what specific steps you can take to sleep better on hot nights? Click here to continue reading.

Conclusion

The temperature of the sleeping environment and of the body is an important—and even a determining—factor when it comes to sleep quality. It’s not just a matter of comfort; it also has a major impact on how you progress through the different stages of sleep and, therefore, on the quality of your sleep.

This is an area where most people can still make significant improvements. Keep your bedroom around 18 degrees and make sure you have the right blankets or duvets. Sounds good in theory? If you don’t have air conditioning, try using a fan. That way, you’ll at least feel like your bedroom is a few degrees cooler than outside.

Temperature, humidity, and ventilation play a major role in determining how much restorative sleep you get each night.

Frequently Asked Questions