Forest Bathing Enhances Sleep, Mood, and Immunity: Insights from Low-Latitude Evergreen Broad-Leaved Forests

Xiangheng Dai¹Dongteng Liao²Jianghua Ouyang³Hongwei Xiao¹Zhongjie Tian¹Liujin Qiu³Jinmei Yang³HAO WANG⁴Daocheng Gong⁴Zhaojia Li⁵Xu Wang⁵Yunsong Xu¹Xiang Fang⁶Jianmin Tan¹Meixiang Wang¹Beidi Zhou¹Huagui Peng^3*Yihua Peng^1*Qiang Wu^1*

• ¹Shaoguan First People's Hospital, Shaoguan, China
• ²Guangdong Medical University, Zhanjiang, China
• ³Tianjingshan Forest Farm of Guangdong Province, Shaoguan, China
• ⁴Jinan University, GuangZhou, China
• ⁵Research Institute of Tropical Forestry, CAF,, GuangZhou, China
• ⁶Utrecht university, Utrecht, Netherlands

Rapid urbanization and environmental degradation have escalated health challenges such as sleep disturbances, mood disorders, and chronic stress. Forest bathing, a practice derived from Japan's Shinrin-yoku, provides immersive sensory engagement with nature, offering both psychological and physiological benefits. Low-latitude evergreen broad-leaved forests, characterized by the unique release of phytoncides and negative ions, may amplify these benefits.Herein, we conducted a prospective cohort study, 36 healthy young participants were recruited via WeChat and assessed within the Tianjing Mountain Forest in Guangdong Province.Participants underwent pre-and post-intervention evaluations using standardized measures: the Athens Insomnia Scale (AIS) and Self-Rating Scale of Sleep (SRSS) for sleep quality, the Profile of Mood States (POMS) for mood, and the Perceived Stress Scale (PSS) for stress. Additionally, routine blood tests, lymphocyte subset profiling, and immune markers-including Aquaporin 9 (AQP9), Heat Shock Protein A6 (HSPA6), salivary immunoglobulin A (IgA), and lysozymewere measured immediately, one week, and one month after the intervention. Results revealed 2 significant improvements across multiple domains. Sleep quality improved substantially, with AIS scores decreasing during the intervention and SRSS scores remaining significantly lower for up to one-month post-intervention. Mood and stress indicators also demonstrated significant improvements, as reflected by declines in POMS and PSS scores. Physiologically, transient increases in hemoglobin and red blood cell counts were observed, while platelet fluctuations normalized by one month. Immune profiling revealed significant increases in total, regulatory, and helper T cells, an improved CD4/CD8 ratio, and elevated B lymphocyte counts at one month.Moreover, serum levels of AQP9 and HSPA6indicators of inflammation and cellular stressdecreased during the intervention, while salivary IgA and lysozyme surged, indicating enhanced oral immune function. Overall, these findings suggest that forest bathing offers immediate and multidimensional health benefits, underscoring its potential as a non-pharmacological intervention for holistic well-being. The study advocates for the integration of natural spaces into urban planning and public health strategies to promote health and wellness in increasingly urbanized populations.This study had been registered at the China Clinical Trial Registration Center (registration number: ChiCTR2500096972; https://www.chictr.org.cn/showproj.html?proj=241942).