Effects of Heatwaves and Tropical Nights on Sleep in Middle-Aged and Older Adults: A Scoping Review

Heatwaves and tropical nights are emerging as significant public health challenges under accelerating climate change, with middle-aged and older adults demonstrating heightened vulnerability. This scoping review maps the existing evidence on how nocturnal heat affects sleep in middle-aged and older adults aged 45 and above, synthesizing findings from experimental and observational studies published in English over the past decade. A comprehensive search of PubMed and Scopus, supplemented by reference screening, identified 31 relevant studies. Data on study design, population characteristics, heat exposure metrics, sleep outcomes, and interventions were charted and synthesized narratively due to methodological heterogeneity. Across studies, elevated nighttime temperatures consistently reduced total sleep time and sleep efficiency, increased wake after sleep onset, and disrupted sleep architecture, particularly REM and N3 stages. Environmental, behavioral, and physiological interventions such as improved ventilation, targeted cooling strategies, and pre-sleep thermal management partially mitigated heat-related sleep disruption. Overall, the findings highlight gaps in standardized exposure metrics and harmonized sleep assessment, providing guidance for future research and public health strategies aimed at protecting sleep health in middle-aged and aging populations amid increasingly frequent extreme heat events.