In 1902, engineer Willis Carrier invented air conditioning modern, but not so that we could sleep better or to combat heat waves: he created it to prevent paper from will be deformed by humidity at a Brooklyn print shop. More than a century later, that machine designed to save ink and paper has ended up regulating something much more delicate: our own sleep.
Sleep with air conditioning. Every summer comes back the same question: Is it a good idea to sleep with air conditioning? And the answer is not as simple as it seems. The cardiologist José Abellán posed an idea that connects with something basic in our physiology: the human body is designed to sleep in an environment where the temperature drops naturally at night, not in one that is artificially frozen for hours.
That’s the key. It is not that air conditioning is “bad” in itself, but that breaking that natural thermal pattern (going from daytime heat to constant and intense cold) can disturb rest more than we think.
What the body asks for while we sleep. Sleep science has been confirming for years something very specific: To initiate and maintain deep sleep, your core body temperature has to drop slightly. This decrease is a biological signal to enter rest. That’s where air conditioning plays an ambiguous role.
Used well, it helps facilitate that process. Misused, it exaggerates and distorts it. The difference is in moderation. Medical organizations and societies in Spain such as the Spanish Society of Pulmonology and Thoracic Surgery recommend temperatures between 22 and 24 degreesprecisely to accompany this physiological descent without forcing it.
The problem is not getting cold, it’s overdoing it. Here is the most common mistake. Many people set the air to 18 or 19 degrees and keep it there all night. This can generate an immediate feeling of relief, but also dry mucous membranes, irritates the throat, congests the nose and can cause micro-awakenings that fragment sleep.
This is what many people describe when they wake up with a dry mouth or a cold feeling. From SEPAR they insist Furthermore, air conditioning greatly dehumidifies the environment, and if the humidity falls too low, the natural defenses of the nose and throat become less effective against particles and microorganisms.
What the organizations say. The health consensus in Spain does not say “do not sleep with air”, but rather “use it with common sense.” Moderate temperature between those 22 and 24 °Cavoid the direct jet to the body, maintain humidity between 35% and 60%, clean filters frequently and do not create extreme differences with the outside temperature.
It is also recommended to use night mode or timer, so that the device slightly raises the temperature in the early morning. This fits with physiological logic: help the body fall asleep, but then let it follow its own thermal rhythm.
The fan is your friend. The alternative that proposes Abellán makes sense within that logic: using air conditioning only to lower the initial temperature of the room and then switching to the fan. This cools the environment without continuing to dry it or artificially cool it all night. “Our body has evolved in a natural environment, and in nature it is normal for the temperature to drop a little at night, so what is totally unnatural, and makes us rest worse, is spending all day with the air conditioning on full blast and the temperature not dropping at night,” clarified.
Other tricks he mentions, such as cooling wrists with cold water or lightly moistening sheets, work because they act on the body’s natural heat dissipation, not against it. They are small physiological shortcuts, not miracle substitutes.
Conclusion: yes, but as a tool. Ultimately, the question should not be whether sleeping with air conditioning is good or bad, but rather how to use. If it is used to create a reasonable environment and then accompany the natural drop in temperature, can improve clearly the rest.
On the contrary, if it becomes a kind of permanent night refrigerator, we are forcing an ecosystem that the body does not recognize as natural. And there it appears the modern paradox: We have the technology to sleep cooler, but sometimes we use it in just the way that makes us sleep (much) worse.
Image | Wikimedia
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