MILWAUKEE - The Milwaukee area has seen a lot of heat so far this summer. Recently we tied or broke the record for warm overnight lows two days in a row. Climate change and a warming world isn't just making our days hotter, it’s also making our nights more restless and potentially dangerous.
A groundbreaking new study published in the journal Nature Communications has a dire warning when it comes to hot summer nights and your health!
Researchers from Flinders University found that rising nighttime temperatures are significantly worsening cases of obstructive sleep apnea (OSA), which is a sleep disorder that affects nearly a billion adults worldwide.
Hot nights = more sleep apnea
What we know:
The data showed a 45% increase in episodes of sleep apnea on the hottest days when compared to the cooler ones.
In 2023 alone, the heat-induced rise in sleep apnea led to the loss of thousands of "healthy life years" across the 29 countries studied. A "healthy life year" is a standard public health measure used by the World Health Organization.
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Simply put: One healthy life year = one year of life lived in full health.
CPAP mask for treating the sleep apnea (Photo by Roberto Machado Noa/LightRocket via Getty Images)
What we know:
The study found a combination of earlier deaths and more years lived with sleep-disruption resulted in over 750 thousand healthy life years lost in 2023 due to warm nights.
There is also an economic hit. The same year saw an estimated $98 billion in economic losses from reduced well-being and workplace productivity due to sleep apnea.
Why you should care:
Obstructive sleep apnea disrupts breathing during sleep and is linked to a higher risk of heart disease, type 2 diabetes, and high blood pressure. A poor night's sleep has been linked to an increased risk of motor vehicle accidents and a significant reduction in workplace productivity as well as overall quality of life.
When nights are hotter, people sleep less deeply and for shorter durations. For those already at risk, especially older adults, men, people with higher BMI, or those in regions without widespread air conditioning, the danger is magnified.
What you can do:
While global policy changes are beyond the reach of most, there are things individuals can do to take action.
Cool your sleeping environment: Use fans, AC, blackout curtains, and even invest in cooling mattress pads.
Maintain a healthy weight: Higher BMI is linked to an increased risk of sleep apnea, so staying active and eating well can help.
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Get screened for OSA: If you snore loudly, feel groggy during the day, or have disturbed sleep, you should talk to a doctor or sleep specialist.
This study is about sleep, but it is also a wake-up call that poor sleep is more than just a personal nuisance; it’s a public health issue, one that is being intensified by climate change.
The Source: Citation: Lechat, B., Manners, J., Pinilla, L., et al. (2025). Global warming may increase the burden of obstructive sleep apnea. Nature Communications, 16(5100). https://doi.org/10.1038/s41467-025-60218-1