The Impact of Rising Nighttime Temperatures on Sleep: Implications for Vulnerable Populations

A national cohort of more than 14,000 U.S. adults shows rising nighttime temperatures are linked to shorter, poorer-quality sleep—threatening population health because sleep disruption raises cardiometabolic and mental-health risk.

The observational analysis of 14,232 U.S. adults combined meteorological, geolocation and multi-source objective sleep data to link nocturnal heat exposure with measurable reductions in total sleep time, sleep efficiency and continuity across millions of nights. Effect sizes were largest among women, Hispanic adults, people with chronic conditions, lower socioeconomic groups and residents of the U.S. West Coast, highlighting subgroup vulnerability.

Physiologically, nocturnal heat impairs heat dissipation, prolongs sleep latency and alters architecture with less deep and REM sleep. Environmental and social drivers—urban heat islands, poor housing insulation, limited overnight cooling and unequal access to air conditioning—amplify exposure and concentrate risk among the most vulnerable.

The report’s model-based projections estimate average Americans could lose roughly 8.5 to 24 hours of sleep per person per year by 2099; these are scenario-driven projections rather than direct observations and should be interpreted accordingly.

Taken together, the observational findings and modeled scenarios provide a clear rationale for prioritizing adaptive strategies that address both heat exposure and sleep health at clinical and community levels.

Key Takeaways:

• Rising nighttime temperatures are associated with shorter and poorer-quality sleep in a national cohort; disrupted sleep poses population-level cardiometabolic and mental-health risks.
• Effects are largest among women, Hispanic adults, people with chronic conditions, lower socioeconomic groups and West Coast residents, reflecting combined physiologic and social vulnerability.
• Model projections to 2099 suggest per-person annual sleep losses that, when aggregated, imply substantial future public-health burden and support targeted heat- and sleep-focused adaptation.