Ночное воздействие жары сильнее нарушает функцию почек и ухудшает качество сна, чем дневное

Heat exposure produces distinct renal effects depending on the time of day, with nighttime heat associated with greater increases in urinary biomarkers of early kidney stress, according to trial findings published in Environmental Research. High ambient temperatures are associated with acute kidney injury and chronic kidney disease progression, but most studies have not examined whether renal responses differ between daytime and nighttime exposure. Kidney function follows circadian rhythms, so the investigators evaluated the effects of passive heat exposure at different times of the day. The randomized crossover trial included 41 healthy adults (23 women; mean age, 24.2 years) who underwent 8-hour daytime and nighttime temperature exposures under controlled laboratory conditions. Heat conditions were 32°C during the day and 30°C at night, compared with a thermoneutral temperature of 26°C. Blood and urine samples were collected before and after heat exposure to assess markers of glomerular filtration, tubular injury, and early kidney stress. Daytime heat exposure increased serum creatinine by 7.67% (95% confidence interval [CI], 4.73-10.61) and cystatin C by 3.05% (95% CI, 0.17-5.93), while estimated glomerular filtration rate (eGFR) decreased by 0.05% (95% CI, 0.02-0.08). At night, heat exposure increased creatinine by 5.23% and reduced eGFR by 0.04%, although the differences between daytime and nighttime effects on these markers were not significant. Nighttime heat exposure had larger effects on urinary markers of early renal stress, increasing insulin-like growth factor-binding protein 7 (IGFBP7) by 58.40% (95% CI, 27.66-89.14), kidney injury molecule-1 by 47.25% (95% CI, 18.91-75.59), and tissue inhibitor of metalloproteinases-2 by 51.88% (95% CI, 22.26-81.51). The increase in IGFBP7 was significantly greater at night than during the day (58.40% vs 17.25%; P =.016). Nighttime heat also reduced sleep duration and sleep quality and lowered heart rate variability. Sleep-related factors partially mediated the renal effects of nighttime heat, accounting for 3.51% to 18.81% of observed changes in selected biomarkers. “This randomized crossover trial reveals distinct diurnal patterns in renal responses to heat exposure, with daytime heat primarily influencing serum renal function markers and nighttime heat predominantly affecting urinary biomarkers of acute kidney injury,” the investigators concluded. “In addition, sleep quality reduction arising from heat exposure at night further promotes renal dysfunction. Therefore, kidney health can be enhanced not only by avoiding daytime heat exposure but, more importantly, by avoiding nighttime heat exposure and improving sleep quality.” The trial is limited by enrollment of only healthy young adults, the short exposure duration, and lack of direct measurements of hydration status and renal hemodynamics. The investigators emphasized that the biomarker changes represent acute physiological responses and should not be interpreted as evidence of sustained kidney injury. References: Liu J, Li Y, Fan Y, et al. Diurnal differences in the effects of heat exposure on renal function: a randomized controlled crossover trial. Environ Res. 2026;307:125547. Published online August 24, 2026. doi:10.1016/j.envres.2026.125547