Hot Weather Makes Us Sleepy, Scientists Claim

In countries like Mexico and Spain, mid-day naps — the so-called siesta — are an integral part of their respective people’s cultural heritage. Yet, an interesting new study finds that taking naps during the day is universal to all humans — at least during hot weather!

As per the results published in the journal Current Biology, it’s not accidental if you find yourself napping more in the summer. Northwestern University researchers speculate that human brains have heat sensors that activate on a hot summer afternoon. As a result, we get sleepy and require rest.

For fruit flies (Drosophila) examined in this research, sleeping during the hottest hours of the day was not a learned behavior but a pre-programmed one.

These tiny insects’ “sleep switch” turned on when temperatures reached 77 degrees Fahrenheit or hotter. The results were somewhat expected after a similar 2020 paper revealed the existence of a possible cold sensor in the brain.

Why is this important?

Well, according to scientists, we have the same temperature sensitivity as fruit flies. However, unlike them, humans constantly try to manipulate their biological and sleeping patterns to accommodate societal norms; the resulting sleep debt has a detrimental effect on our health.

Moreover, it is precisely due to these work-time adjustments that we cannot detect instinctive mechanisms such as this one.   

We already know how daylight influences the production of melatonin — the sleep hormone. Yet, which neural pathways govern the relationship between seasonal temperature and sleep is still a mystery to us.

Besides sleep changes, temperature also influences behavioral patterns in all living beings. For instance, bears hibernate during winter while it’s cold. And they aren’t the only ones.

All in all, more research is needed to get to the bottom of this amazing find.