A recent study published in One Earth identified a connection between higher outdoor temperatures and reduced sleep duration.
In this project, scientists from Denmark and Germany collected more than 7 million sleep records from the wristbands of more than 47,600 people in 68 countries around the world. Gather factors include sleep duration at night and sleep timing (onset, offset, and midsleep).
This data is then compared with climate and meteorological information in according regions.
The analysis suggested that a rise in temperature during the nighttime lower sleep duration, irrespective of location. These effects escalate when the temperature goes up.
The likelihood of lowered sleep is higher when the temperatures go beyond 10°C. In addition, those who sleep at temperatures under 10°C have 14 minutes more each night than those in temperatures above 25°C.
Not every demographic group is affected in the same way. The effects can be seen more obvious in older people than in younger ones.
People in underdeveloped or developing nations were nearly 3 times more affected than those in more developed countries. And men were considerably less affected than women.
Certain factors may explain the link between outdoor temperatures and sleep quality. In general, a higher temperature may reduce deep sleep and increase arousal.
However, it can be hard to establish causal links as many other factors may contribute to this effect.
Intensified effects in the elderly would be caused by a compromised thermoregulatory response to surrounding temperatures, which results in a higher sensitivity to increased temperatures.
The fat can explain the gender differences in that subcutaneous fat in women is thicker, which affects heat loss at night. In addition, core body temperatures in women tend to reduce earlier than in men at night, which makes them more prone to surrounding temperatures.
Sleep problems may affect mental health and increase the risk of accidents when working or driving. More importantly, chronic sleep deprivation may increase the risk of other medical conditions, such as depression, high blood pressure, diabetes, and obesity.
In the long run, lowered sleep duration would lead to an intensified stress response, affect immunities, as well as disrupt memory consolidation. Sufficient sleep plays an essential role in healthy restoration, repair, as well as development.
About the drawbacks of the study, it is important to note that those who use sleep trackers may be wealthier and have better economic conditions. Therefore, they would have better access to air conditioning.
Future research should focus more on underdeveloped countries in Africa and Asia to learn more about this link.