How Climate Change Affects Our Sleep (and Why It Won’t Get Better)

Forty-four hours, or eleven nights. Less than seven hours of sleep: This is what everyone currently loses at bedtime due to higher temperatures, according to a study conducted by Danish researchers from the University of Copenhagen between 2015 and 2017 and published in review one land May 20, 2022.

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To do its work, the Danish team collected data provided by a sample of 47,000 people from 68 countries, fitted with a sleep monitoring bracelet, which they compared with local meteorological data. That is, in total, about seven million nights of sleep were recorded. At the end of their work, they were able to prove it from 25°against When measured outdoors, the probability of not enjoying restful sleep is multiplied by 3.5. In fact, while the ideal temperature for sleeping is around 19°C, higher outside temperatures delay the moment of sleep (because we need our body to cool down to fall asleep) and advance our waking clock.

This deterioration in sleep time could increase in the future: scientists from the University of Copenhagen have demonstrated that rising temperatures caused by global warming could deprive us of 50 to 58 hours of sleep per year by 2099.

Among those affected first, women and the elderly: Under similar conditions, women’s basal body temperature drops earlier in the evening compared to men, the study shows, which could expose women to very high temperatures when they normally start to sleep. The body of the elderly regulates heat less effectively than the young.

The researchers argue, while acknowledging that they cannot prove it, that residents of developing countries could be more anxious, because they are less equipped with an air conditioning system.

In addition to severe mental health consequences, a decrease in cognitive performance, a decrease in productivity, an increase in absenteeism, a reduced efficiency of the immune system, and a higher risk of hypertension. And more depression and suicidal behavior.

Sleep deprivation also delays reaction times, increases the risk of accidents, inhibits the neural encoding of new experiences in memory and limits the clearance of neurotoxic metabolites from the brain associated with aging and neurodegenerative diseases. Finally, lack of sleep will significantly increase feelings of hunger: In another study published in March 2017, scientists from the University of Pennsylvania demonstrated that nights of less than six hours favor the production of ghrelin, the digestive hormone that stimulates appetite, and reduces. Leptin regulates body fat storage and appetite by controlling satiety.

The publication of this study comes at a time when the heat wave raging in India and Pakistan has already caused 90 deaths. According to scientists from the World Weather Attribution (WWA), the network of scientists leading in attributing extreme events to climate change, this heat wave is thirty times more likely to be caused by climate change.