What happens when we don't sleep because of the heat?

The main effects are immediate: tiredness, drowsiness, and a bad mood. Seven hours of sleep are rarely achieved.

di |
pexels kampus 5990936 scaled

Heat is considered one of the most important causes of insomnia and sleep disorders, especially during heat waves, and when we can't sleep well because of the heat, our body and brain suffer from it already the next day. One of the studi more complete on this problem dates back to 2020, and was carried out by a team of scholars led by Kelton Minor, published in the journal Nature, analyzing further 7 million nights of sleep recorded via body-worn devices 68 CountriesThe authors estimated that nighttime temperatures above about 25 ° C are associated with measurable reductions in sleep duration and significantly increase the likelihood of sleeping less than 7 hours. Sleep loss is mainly due to a delay in falling asleep rather than an early awakening and the effects are stronger in the elderly, women and populations living in areas with fewer economic resources. 

The mechanism

Heat works in a unique way because it interferes with a fundamental biological mechanism of sleep: before falling asleep, the body must slightly lower its internal temperature. When the room is too hot or humid, this process becomes more difficult. Consequently:

  • We fall asleep more slowly.
  • You wake up more often during the night.
  • Deep sleep and, to some extent, REM sleep are reduced.
  • You feel less rested when you wake up.

The most common effects

The most common effects are:

  • Tiredness and drowsiness during the day.
  • Difficulty concentrating and memory, with more errors in daily activities.
  • Irritability and worsening of mood.
  • Reduced physical performance, because muscle recovery is less effective.
  • Headache or feeling of heaviness.
  • Greater perception of the stress..

During sleep, blood pressure drops by approximately 10–20% compared to daytime values: this phenomenon is called dip Nocturnal. When sleep is short or fragmented, this decrease can be reduced, and the cardiovascular system remains more activated during the night.

If sleep disturbed by heat continues for several days, the following may also appear:

  • Increased cardiovascular fatigue, especially in the elderly or people with heart disease.
  • Worse blood sugar control in predisposed individuals.
  • Weakening of the immune defenses.
  • Worsening of conditions such as anxiety or depression.

How to sleep better when it's very hot

The most important things to do to sleep better when it's very hot are:

  • Keep the room between about 18 and 24 ° C if possible.
  • Ventilate during the cooler hours and darken the windows during the day.
  • Take a warm shower before going to bed.
  • Use sheets light cotton or linen.
  • Avoid large meals, alcohol, and intense physical activity in the evening.
  • Maintain good hydration throughout the day.

Here you find all the tips for sleeping better during very hot nights. 

Read also: 

Want to see a selection of our news?

Don't Waste