Why Does Heat Make You Sleepy?

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We’ve all been there. It’s a hot sunny day and while you would like to be out there playing beach volleyball – or something similar – you feel so drowsy you can barely get up from your spot on a beach towel. Or the long meeting in a hot stuffy room is sending you to sleep, and it is not even that boring. Most people do find that heat makes them tired. But why does heat make you sleepy?

In answering the question “why does heat make me tired” there are several possible reasons that you really start dragging when the going gets hot, and several ways you can try to combat this heat related fatigue and stay alert and energized despite the heat. Here we are going to take a closer look at them.

Why Does Heat Make You Tired?

Factors affecting sleep - heat is one of them

As we mentioned, there are several reasons heat will make you tired, including all the following:

Sweating and Dehydration

When you start to get hot your body reacts by sweating. When you sweat you lose fluids rapidly. Rapid fluid loss leads to dehydration, and once you are at that stage your body – and mind – begins to feel tired and sleepy. The fact that your body must expend energy to sweat only adds to the drowsiness you feel.

The key to avoiding this – and the other, more serious health consequences of dehydration like kidney problems or seizures – it is a must that you remain hydrated in the heat. This includes when you are in very warm indoor spaces, even in the colder months.

To assist you in remembering to drink enough fluids – and to ensure you always have them at hand – invest in a smart water bottlelike the Hidrate Spark 3. This reusable bottle holds 20fl oz of your favorite hydrating beverage and tracks your water intake, lighting up when it is time for you to drink more. It is a good idea to always keep a smart bottle like this at hand, especially if you, like many of us, mean to ensure you stay hydrated but get busy or distracted and forget to drink.

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Excess Melatonin

When you are out there sunbathing, or just out in the sun in general, your body temporarily stops producing melatonin. When you head back into the shade it starts the process up gain, but in overdrive. This excess melatonin makes you feel sleepy, in much the same way a melatonin supplement is designed to at night.

You can combat this by ensuring that you do not stay out in direct sunlight for too long, and that you seek shade, and water, at least every 15-20 minutes on hot sunny days.

Lowered Blood Pressure

When it is hot – and thus you are hot – your blood pressure drops too. This drop in blood pressure slows you brain activity down and leads to that drowsy feeling.

In itself this is not too much of a problem but if you also experience sudden headaches or nausea you should seek medical help as soon as possible as these are often early warning signs of heat stroke or severe dehydration, both of which can have serious, and even deadly, consequences.

What Makes You More Sleepy, Hot or Cold?

Being excessively hot or too cold will often make you feel sleepy. Why heat makes you drowsy is something we just covered but being too cold can too. When you are too cold your body shivers to try to stay warm, expending energy and making you feel tired. Therefore, for better sleep you should always keep your room cool – not cold – whatever the weather is outside.

The ideal room temperature at any time of year, according to sleep experts, is around 65 – 67 degrees Fahrenheit and so you should adjust your HVAC systems accordingly to get the most comfortable night’s sleep.

Can Heat Drain Your Energy?

It sure can. All that sweating, the drop in blood pressure and the extra melatonin that is introduced into your body when you do seek shade all sap your energy and leave you feeling fatigued.

Does Gas Heat Make You Tired?

Although gas heat is less common in the US than it once was those of you that do still have gas heated homes – or a gas-powered fireplace – may have noticed that after a while the toasty warm heat seems to start putting you to sleep. This is because not only is gas heat usually very powerful – often getting hotter faster than electric heat – it can sap moisture from the air as well as your body.

However, tiredness can also be a sign that there is something wrong with your gas heat. Tiredness that is accompanied by shortness of breath, headaches, confusion, or a sudden inability to stay awake at all may be signs of a carbon monoxide leak, something that can be deadly.

In fact, according to the CDC at least 400 Americans die every year from accidental CO poisoning caused by faulty heating systems. To avoid this, ensure you have a working CO detector near all your heating sources and that you get your heating system checked at least once a year by an HVAC professional.

Why Do I Get Hot When I’m Tired?

There are several reasons you might get hot when you are tired. Some of them are normal, including just that you are starting to become comfortably drowsy and your body sweats slightly in response.

You may also be making use of bedding that is too hot. The ideal bedding for cool sleep are choices made using a breathable, even cooling material like cotton or bamboo. We love these LuxClub Sheets, as they are 100% cooling bamboo, a material that also has natural antimicrobial properties, is very durable and super easy to care for.

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If you are often very hot when tired it may be something to discuss with your doctor, as feeling excessively hot may be a sign of a medical issue like thyroid problems or RLS (restless leg syndrome.)

What is Summer Lethargy?

Summer lethargy is just the term for the drowsy feeling the heat can cause for all the reasons we have described. It is the reason a lot of the time in the summer all we want to do is hang out and relax. which is great, unless you have to go to work!

How to Beat Heat Related Tiredness

The biggest key to staying alert – and healthy – in any kind of heat is hydration. In addition to the smart water bottle we suggested earlier you can also make use of an app to track your water intake, or even a smart wearable like the Bellabeat Leaf. This tracker is multi-functional it tracks your steps, distance moved, calories burned, sleep patterns, reproductive health, menstrual cycle and even stress levels.

Bellabeat Leaf Urban Smart Jewelry Health Tracker, Urban Gray / Silver

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What you drink is key as well. Coffee or tea may seem to cool you down – especially iced coffee – but caffeine is dehydrating, which is why sodas will not help much either. Ideally you should stick to water as far as possible and flavoring it with real fruit is a great way to make that a more palatable thought if plain water is not very appealing to you.


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