Rising temperatures – deteriorating productivity: An examination into day-to-day dynamics of temperature, sleep, and perceived productivity

In the context of climate change, rising nighttime temperatures may impair sleep quality and, in turn, affect daytime productivity. We conducted a 2 to 3-week longitudinal ecological momentary assessment (EMA) study with 82 participants and asked them multiple times per day how they perceived their productivity. We delivered EMA prompts via smartwatch; Apple Watch captured heart rate and physical activity. Using Oura Rings, we monitored daily sleep quantified via a composite sleep quality score. Additionally, temperature, relative humidity, and CO2 were measured in the bedroom during the night (AIR CO2ntrol 5000). Assessments took place in Austria during July and August 2025 providing data for 1189 nights in total. Multilevel models at the day level (night t predicting day t+1) showed that higher bedroom temperatures at night were associated with lower sleep quality and, subsequently, lower subjective productivity the following day. Furthermore, sleep quality was positively correlated with subjective productivity. Scalable interventions helping to mitigate heat during sleep such as cooling strategies or sleep environment adaptations are highly warranted.