Table 2.

Thermotherapy for insomnia.

Therapy	Evaluation item	Evaluation results
warm water immersion	Representative Study Design	Literature	Population	N	RCT	Placebo effect excluded	Objective biomarkers	Follow-up
		(88)	(e) healthy adults	11	Yes	No	Yes	No
		(96)	(b) adults	28	Yes	No	Yes	No
		(97)	(c) rheumatoid arthritis patients	54	Yes	No	No	No
		(98)	(b) adults with daily stress and poor sleep quality	25	Yes	No	Yes	No
	Main Clinical Findings & Safety	Warm bath/footbath may improve sleep quality and shorten sleep onset; best around 40–42°C for ≥10 min, 1–2 h before bed (92, 94). Safe and low-cost; avoid burns/falls.
	Limitations	Small, short studies; varied methods; mostly subjective outcomes; limited blinding/placebo control.
	Evidence Level	Emerging. Controlled evidence suggests benefit, but certainty is limited by small studies, heterogeneity, risk of bias, and lack of robust large sham-controlled RCTs.
Periocular warming	Representative Study Design	Literature	Population	N	RCT	Placebo effect excluded	Objective biomarkers	Follow-up
		(87)	(e) healthy male volunteers	18	Yes	Yes	Yes	No
		(89)	(a) diagnosed by DSM-5 (b) individuals with sleep difficulty	38	No	Partly yes	Yes	No
		(90)	(b) female workers	64	Yes	Yes	Yes	No
	Main Clinical Findings & Safety	May improve sleep onset, sleep quality/WASO, and bedtime anxiety; well tolerated with no major safety issues reported.
	Limitations	Small studies, short duration, limited insomnia-disorder data, no long-term follow-up, some non-PSG measures and possible bias.
	Evidence Level	Emerging. Sham-controlled evidence suggests benefit, but certainty is limited by sample size, indirect populations, and short follow-up.