Distinguishing hot flashes and night sweats: a mixed-method analysis

This study aims to differentiate hot flashes (HF) and night sweats (NS) as distinct vasomotor symptoms (VMS) by integrating physiological, self-reported, and qualitative data. Specifically, we investigate (1) whether participants distinguish between HF and NS, (2) how subjective reports of NS correspond to objective physiological measures, and (3) whether HF and NS exhibit different associations with stress, depression, and sleep.

Data were drawn from a study on brown adipose tissue and HF (n = 274, ages 45-55). Participants answered questions regarding lifestyle, well-being, and menopause experiences, and wore skin conductance (to detect HF and NS) and activity monitors overnight. Questions about HF and NS experience were analyzed with thematic analysis. Objective NS scores were compared with subjective reports. Logistic regression analyses were used to compare subjective and objective VMS to stress, depression, and sleep variables.

Qualitative responses revealed that participants perceived NS as distinct from HF, describing NS as prolonged, full-body sweating events, often without the intense heat or anxiety typical of HF. Objectively, NS were significantly longer than HF (mean: 60.5 vs 3.4 min) and occurred earlier in the night ( P = 0.02). Self-reported NS corresponded with objective NS counts ( P = 0.04). Only subjective VMS were significantly associated with stress (NS: 1.04, 1.00-1.09), depression (HF: 1.11, 1.02-1.20; NS: 1.12, 1.04-1.20) and sleep (HF: 1.28, 1.09-1.50).

Findings suggest that NS and HF represent distinct phenomena rather than variations of the same symptom. The results underscore the need for separate criteria for NS in research and clinical practice, as NS may have unique health implications beyond those of HF.