A survey of citizens from Nagoya in central Japan has shown that rising summer nighttime temperatures have a negative effect on population health.

Over the summers of 2011 and 2012, more than 1,200 residents completed a survey regarding their sleep quality. The findings indicated that when the daytime temperature exceeded 24.8 degrees Celsius, there was an increase in nighttime sleep disruption. The research results were released in the publication Sleep and Biological Rhythms.

The number of population health years lost using the disability-adjusted life year (DALY) metric was comparable to the outcome of heatstroke. This emphasizes the significance of controlling rising daytime temperatures and offering ways to create healthy evening temperatures so people can sleep well.

In total, over the course of around 10 days each year, 574 individuals in 2011 and 710 adults in 2012, who were typical of the age and sex ratio of Nagoya′s population, answered an online survey.

According to experts, the survey, known as SQIDS2 (sleep quality index for daily sleep), an updated version of PSQI (the Pittsburgh Sleep Quality Index) was widely used. It evaluated seven factors, including the subjective quality of sleep, how soon participants slept off, and the usage of sleep aids. 

The research group found that daily sleep disturbance increased when the daytime minimum temperature rose above 24.8 degrees Celsius. Younger men had more difficulty falling asleep than older men, and there was a significant difference in sleep disruption between age groups among the male subjects.

Thus, the study helps quantify the harm caused to the sleeping ability and body due to climate changes and guides better sleep.

(Source: https://www.hindustantimes.com/lifestyle/health/hot-summer-nights-have-bad-impact-on-health-survey-101664860918577.html)