Short-term effects of urban versus forest bathing on stress, mood, sleep, immune function, and metabolic health: a randomized, open-label, 2 × 2 crossover trial.

Abstract

Evidence regarding the effects of forest bathing on young adults, particularly in low-latitude regions, remains limited. A more comprehensive understanding of its psychological and physiological impacts is needed to inform its potential role in public health. To compare the short-term effects of forest versus urban exposure on stress, mood, sleep quality, immune-related parameters, and metabolic markers in healthy young adults. In this randomized, open-label, 2 × 2 crossover trial, 36 participants were assigned to forest-urban or urban-forest sequences with a 1-week washout period. Participants walked 2.5 km twice daily in each environment. Psychological scales and fasting blood samples were collected before and after each intervention. Linear mixed-effects models accounting for period and sequence effects were applied. Forest bathing significantly reduced perceived stress (PSS: 22.3 to 20.7) and mood disturbance (POMS: 104.6 to 93.2), and improved sleep quality (SRSS: 20.5 to 18.0) and insomnia severity (AIS: 6.2 to 4.8), whereas no comparable improvements were observed following urban exposure. Hematological analyses revealed modest reductions in total white blood cell count and selected leukocyte subsets after forest bathing, with values remaining within physiological ranges. Forest exposure was also associated with small decreases in fasting blood glucose and log-transformed triglycerides. In contrast, DHEA-S levels increased following urban exposure but remained stable during forest exposure. In healthy young adults, short-term forest bathing was associated with robust improvements in psychological well-being and sleep quality, accompanied by modest physiological modulation compared with urban exposure. These findings support the potential role of forest environments as a complementary strategy for stress reduction, while the clinical significance of short-term biological changes warrants further investigation. This study was registered at the Chinese Clinical Trial Registry (Registration number: ChiCTR2500096972).