Forest bathing reduces stress and improves sleep more than urban exposure in young adults

Sleep Evidence: RCT · n=36 · randomized, open-label, 2 × 2 crossover trial with 1-week washout period 2026-08-28

A randomized trial of 36 healthy young adults found that two 2.5 km walks per day in a forest environment significantly improved perceived stress, mood, sleep quality, and insomnia severity over one week, whereas urban walking produced no comparable improvements.

This randomized, open-label, 2 × 2 crossover trial enrolled 36 healthy young adults who completed forest and urban walking interventions (2.5 km walked twice daily) separated by a 1-week washout period. Perceived stress scores decreased from 22.3 to 20.7 after forest bathing versus no significant change after urban exposure; mood disturbance (POMS) fell from 104.6 to 93.2 in the forest condition only.

Sleep quality improved substantially in the forest group (SRSS: 20.5 to 18.0), and insomnia severity declined from 6.2 to 4.8—gains not replicated after urban walks. Blood samples revealed modest physiological shifts: total white blood cell counts and selected leukocyte subsets decreased slightly after forest exposure, remaining within normal ranges, and fasting glucose and triglycerides showed small decreases. Urban exposure paradoxically increased DHEA-S (a stress hormone marker), whereas forest exposure left it stable. The study design (crossover with washout) and matched walking distance (2.5 km) strengthened internal validity, though the small sample size and short intervention window (one week per condition) limit generalizability to longer-term effects or diverse populations.

Takeaway

Short-term forest walking may be associated with measurable improvements in stress perception, mood, and sleep quality in young adults, whereas urban walking showed no comparable benefit.

Beyond the headline stress and sleep improvements, the study revealed a striking contrast in hormonal response: DHEA-S (dehydroepiandrosterone sulfate, often elevated during stress) increased after urban exposure but remained stable during forest exposure, suggesting the forest environment may dampen acute stress physiology in a way urban settings do not. The white blood cell reductions observed after forest bathing—including modest decreases in neutrophils and lymphocytes—align with prior

Takeaway · Cadence

: prior forest bathing research showing immune modulation; however, the reductions were small and remained within healthy ranges, making clinical significance uncertain. The psychological gains (mood, stress, sleep) were considerably larger than the biological ones, implying the mental and behavioral shifts may be the primary mechanism. Notably, this study was conducted in a low-latitude (subtropical) region, filling a gap in the literature: most forest bathing research comes from Japan and higher latitudes. The one-week washout period was sufficient to prevent carryover, lending credibility to the crossover design, though a longer follow-up would reveal whether gains persist after participants leave the forest environment.,

Read the full breakdown in the app

The deeper explanation, the effect sizes and caveats, and what this means for your own sleep, exercise and reading — read it inside Cadence.

Open in Cadence →

References

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. — Environmental health and preventive medicine (Read the original)

#forest-bathing #nature-exposure #stress-reduction #sleep-quality