Thermoregulation During Sleep & Why a Cool Sleep Environment is Optimal

You may not know, but the temperature you are sleeping in can greatly affect your quality of sleep. As you fall into a deep, peaceful slumber your body temperature cools down (or should anyway.) That's because there's less blood flow to the core musculature. You'll notice if you ever try to sleep in the heat it is more difficult to attain quality sleep.

Conversely if you are exercising, your body wants a higher temp - the core temp will rise, because there is more blood flow. The increase in body temp gives you energy. Obviously when we are trying to sleep we don't want a rush of energy. That's why our bodies internal clock starts trying to cool ya down.

Human beings are endotherms, which means under normal circumstances, we are able to self regulate our temp. Extreme heat/cold/severe illness that would cause a temp >104.9 degrees Fahrenheit or <92.3 degrees will generally cause injury or death, if not promptly attended to.

Humans have two zones that need to be regulated: the core & the shell

• Core is composed of the abdominal, thoracic, and cranial cavities, home to the vital organs. Regulated by the brain
• Shell temperature includes the skin, subcutaneous tissues, and muscles. It is more affected by external temperature.
  The core is able to conserve or release heat through the shell

The body is a fantastic self regulator - if the core temp is too high, blood vessels dilate to release heat to the skin through evaporative sweat. Conversely, if too cold, blood vessels dilate to conserve heat.

Upon awakening, the body temperature is at its baseline of 98.6°F. Throughout the morning and through the late afternoon, the hypothalamus can increase that up to 100.4 degrees, which gives you energy, helping you stay alert. Again, this is partly why exercising is energizing, as the rise in body heat makes you feel more awake.

Have you ever wondered why your body craves an afternoon nap? That's because by mid-afternoon the body temp starts to gradually lower prepping you for sleeping later. By 5 am, you’re at your lowest body temperature (96.4 degrees.)

However, these temp changes are relative to a person's 24 hr circadian rhythm which, depending on what time you go to bed, is different for everyone.
For instance, "early birds" experience an earlier body temperature peak than night owls do.

So, as you have hopefully surmised at this point, your temp does actually change during the day and night - from the peak temp during the day (which provides you energy and mental alertness) to your lowest temp typically occurring just before you wake up. Overnight (or whatever time you're sleeping based off your individual sleep cycle), you'll therefore experience a core temp drop of ~2°F.

SO YOU MAY BE WONDERING, WHY IS IMPORTANT FOR MY TEMP TO FALL DURING SLEEP??

IT IS BECAUSE YOUR BRAIN NEEDS TO SHUT DOWN!

Thermoregulation is less efficient during deep sleep than light sleep. During deep sleep, your brain actually stops working to regulate your body temperature. This is to give your hypothalamus a much needed break!! In order for this ideal sleep to occur, a temperature in the
mid-sixties will work. Everyone is different though, so experiment to find the temperature that works best for you.

It should be cool enough to help you fall asleep without waking up a few hours later shivering while not being too warm and waking you up from sweating.

Here are some tips to help you sleep more comfortably without being too hot:

• Use less bedding.
• For your bedding and clothing - look into more breathable fibers like cotton or linen
• A warm (not hot) bath/shower helps to actually helps cool down you before sleep. This is because as you step out from the water, the moisture quickly evaporates causing a cooling effect. Try this one hour before bed for optimal effect.

In summary, a cool sleep environment is needed for deep sleep to occur so that our brain can rest. That way you actually do wake up refreshed, alert, and ready for the day!

Info source: https://www.tuck.com/thermoregulation/
Pictures are my own!