As the planet warms, many people will find it much harder to get a good night’s sleep.
A study based on a survey of 750,000 people living in the US has found that when temperatures are high, people report getting less sleep. Elderly and poorer people find it particularly hard to sleep on hot nights. This may be partly because they cannot afford air conditioning, says Nick Obradovich at Harvard University.
Obradovich and his colleagues estimate that there will be a big increase in sleep loss as the planet warms – not least because nights are warming faster than days. For every 100 people in the US, there will be six extra sleepless nights per year by 2050 if global warming continues at its current rate.
Heat stress is known to have numerous effects on people’s health and ability to work. “The way people recover from heat is having a good night’s rest,” says Obradovich. “Sleep loss may play a role in loss of life.”
Although many people in the US may be able to adapt, the impact will be much greater for those in hotter places such as South East Asia, says Tom Matthews at Liverpool John Moores University in the UK. Many people in these countries cannot afford air conditioners, and if they did all buy them, it could lead to a massive rise in carbon emissions, he says.
We may already be losing sleep as a result of climate change, given that the planet has warmed by more than 1°C since pre-industrial times. Animals are already known to be affected – some are spending less time hibernating, or even not hibernating at all.