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Sleep Sensation via Thermoregulation

Updated: Oct 19, 2019

Melatonin production vs. core temperature

Welcome, welcome friends and family! Today we discuss body temperature and sleep. Is it better to be cold or hot? Should you be a thermostat guardian, or rethink your temperature settings?

We have two zones to regulate, our core temperature and our shell temperature. The core temperature is governed by the brain and regulates the abdominal, thoracic, and cranial cavities, which contain the vital organs. The shell temperature, more affected by external temperature, includes the temperature of the skin, subcutaneous tissues, and muscles. Our core temperature is maintained within a fairly small range from the resting temperature of 98.6. Temperatures greater than 104.9 degrees Fahrenheit or below 92.3 degrees generally cause injury or death. The core is able to conserve or release heat through the shell. When our core temperature is too high, blood vessels in the skin dilate and heat is lost through their walls. Sweat is also produced; it evaporates and lowers temperature. If we become too cold, the blood vessels constrict, conserving heat. Blood is preferentially shunted to the vital internal organs and away from the skin and peripheral structures like limbs.

Our body temperature plays an important role in regulating circadian rhythm—the natural clock that determines your energy highs and lows throughout the day; including when it’s sleepy time. The onset of sleep is linked to cooler body temperatures, while elevated body temperatures may impede upon our ability to initiate and maintain sleep. After waking, the hypothalamus—the tiny pea-sized portion of the brain responsible for regulating body temperature, hunger, the release or hormones, and other vital functions—works on driving our body temperature from its baseline of 98.6 degrees up to approximately 100.4 degrees. This gradual rise occurs during the morning through late afternoon, and helps you feel energized and alert. However, by 3:00PM, things begin to about-face. As bedtime gets closer, our internal temp takes a dive—and we start to feel drowsier and more fatigued (hello afternoon crash!). The temperature continues to drop past your bedtime and doesn’t actually bottom out until it hits approximately 96.4 degrees; roughly two hours before waking.

We all have different circadian rhythms, based on lifestyles and life requirements, yet one thing remains constant; lower temperature let our bodies know when sleepy time is on its way, and higher temperatures tell our bodies it’s time to wake up and be active. Sending the appropriate signals help maintain a good sleep cycle.

Tips: 1) Turn down the thermostat at night. Start at 65 degrees and work your way up as needed, if too cold

2) Using breathable bedding such as cotton, linen, or wool, instead of synthetics such as polyester. Natural fibers help wick away moisture (sweat), which may cause you to wake up damp and shivering.

3) Try to exercise early in the morning (early in the day is best) or between 5:00 P.M. and 7:00 P.M. Exercise elevates body temperature, and we need time to cool off, or have the consequence of throwing off our temperature cycle.

4) Taking a warm bath at least an hour before bed. Wait . . . warm bath? Won’t that be like exercise? Nope. While warm in the bath, once out, we will quickly cool down as the moisture on our skin evaporates (just like sweating). The reduction in temperature tells the body sleepy time has approached.

Remember, Better Sleep is a Better You!

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