Behind the Forecast: How temperatures affect your sleep

Listen to Science Behind the Forecast with Meteorologist Tawana Andrew every Friday on 89.3 WFPL at 7:45 a.m.
Listen to Science Behind the Forecast with Meteorologist Tawana Andrew every Friday on 89.3 WFPL at 7:45 a.m.
Published: Oct. 16, 2020 at 9:25 AM EDT
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LOUISVILLE, Ky. (WAVE) - Sleep is a vital part of our everyday life. The weather can significantly impact our sleep patterns.

Doctors have been studying the correlation between colder weather and changing sleep patterns for centuries. Medieval doctors believed that sleep “cooled” our bodies and connected that to the belief that cold and hot “humours” like bile and phlegm controlled our health.

According to the National Sleep Foundation, our body temperatures shift up and down as throughout our days. The pattern of rises and falls influences our sleep cycle. As we begin to fall asleep, our temperatures decrease, reaching their lowest levels around 5:00 AM, then climbing through the morning. Most people see around a two-degree drop in core temperature as they sleep. If your bedroom is too hot, that could prevent your body’s temperature from falling, causing restless sleep. Blasting your heater or furnace during the winter months can ruin your sleep cycle.

The usual effects of heat and cold on sleep are less rapid eye movement sleep (REM) and slow-wave sleep (SWS), according to a 2012 study. Researchers found that hot and humid weather led to less refreshing sleep, waking up multiple times during the night, and less deep sleep. Participants reported good sleep and feeling rested when sleeping in colder conditions; however, their heart rates and blood pressure were higher.

A 2019 study broke down how high temperatures can affect our sleep quality. It found that hot temperatures affected one’s ability to fall asleep, sleep satisfaction, calmness, and sleep adequateness. Researchers found that sleep quality was best at 89.6°F, followed by 82.4°F. The study also observed that the quality of sleep was worst at 96.8°F and 100.4°F.

It’s not just temperatures; the lack of sunlight as the days get shorter during the winter months can also impact our sleep at night. Natural light influences our body’s normal wakefulness and sleepiness cycle, also known as our circadian rhythm. 

When the sun sets earlier during the winter months, this triggers our bodies to produce melatonin, causing us to feel sleepy and our core temperatures to fall.

One study found that people with sleep apnea slept longer when the room was near 61° compared to 75°. Experts recommend having your room temperature between 60° and 67° for optimal sleep. Slightly higher temperatures, between 65° and 70°, is recommended for toddlers and babies.

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