Sauna for insomnia
Evidence review
Overview
Raising body temperature with a hot bath 1-2 hours before bedtime improved sleep continuity and sleep onset in small studies of older women with insomnia and older patients with vascular dementia (summarized in a 2002 systematic review of 3 crossover studies), and a meta-analysis of mostly non-insomnia samples found improved sleep quality and efficiency with 104-108.5 F water. The proposed mechanism is the subsequent fall in core temperature. No trial has tested sauna bathing in people with diagnosed insomnia, and two heat-therapy trials that measured sleep as a secondary outcome found no improvement.
Key findings
- Hot (104-104.9 F) vs lukewarm baths 1.5 h before bed improved sleep continuity in older female insomniacs (Dorsey 1996, crossover, n=9)
- Passive heating at about 104 F for 30 min, 2 h before bed, reduced sleep latency and wake after sleep onset in insomniac patients with vascular dementia (Mishima 2005, n=13)
- Meta-analysis of 17 studies (13 pooled): 104-108.5 F bath or shower 1-2 h before bed associated with better self-rated sleep quality and efficiency (Haghayegh 2019)
- Systematic review of 3 crossover studies: a 104-105.8 F bath to mid-thorax for 30 min in the evening increased slow-wave sleep and perceived sleep quality in older women with insomnia (Liao 2002)
- 8 weeks of regular sauna in chronic tension-type headache did not improve sleep vs control (Kanji 2015, n=37)
Every study we reviewed
5 found benefit · 2 found no effect
Each study was checked on PubMed. The colored edge shows the direction of the result. The research library lists 9 studies on insomnia, across all heat and cold therapies, including case reports and older work not graded here.
Effects of passive body heating on the sleep of older female insomniacs.
Dorsey CM et al. J Geriatr Psychiatry Neurol. 1996. PubMed 8736588 · DOI
- Who
- older women (60-72) with insomnia
- What
- hot vs lukewarm bath 1.5 h before bedtime on consecutive nights
- Protocol
- 104-104.9 °F
- Measured
- polysomnographic sleep continuity, slow-wave sleep, subjective sleep
- Result
- Significant improvement in sleep continuity and a trend toward more slow-wave sleep after hot baths; subjects rated sleep significantly deeper and more restful. No effect sizes given in abstract.
- Limitations
- n=9; two nights; bath rather than sauna
Core body temperature and sleep of older female insomniacs before and after passive body heating.
Dorsey CM et al. Sleep. 1999. PubMed 10566907 · DOI
- Who
- older women (60-73) with insomnia
- What
- hot bath 1.5-2 h before bedtime on at least two nights vs baseline nights
- Protocol
- 104-104.9 °F
- Measured
- core temperature rhythm and sleep
- Result
- Hot baths delayed the core-temperature rhythm phase; this delay paralleled improvements in sleep quality. No effect sizes given in abstract.
- Limitations
- uncontrolled; small; short exposure; bath rather than sauna
Passive body heating ameliorates sleep disturbances in patients with vascular dementia without circadian phase-shifting.
Mishima Y et al. Am J Geriatr Psychiatry. 2005. PubMed 15879585 · DOI
- Who
- elderly insomniac patients with mild-to-moderate vascular dementia (mean age 76.9)
- What
- passive body heating by immersion to mid-thorax for 30 min beginning 2 h before bedtime, 2 days
- Protocol
- about 104 °F · 30 min
- Measured
- actigraphic sleep latency, efficiency, wake after sleep onset
- Result
- Sleep latency decreased, sleep efficiency increased and wake time after sleep onset decreased (significant); core temperature rose about 0.8 C (1.4 F).
- Limitations
- uncontrolled; 2-day exposure; small; bath rather than sauna
Before-bedtime passive body heating by warm shower or bath to improve sleep: A systematic review and meta-analysis.
Haghayegh S et al. Sleep Med Rev. 2019. PubMed 31102877 · DOI
- Who
- 17 studies of before-bedtime warm shower or bath (13 pooled), mostly not limited to insomnia
- What
- water-based passive body heating before bedtime
- Protocol
- 104-108.5 °F · as little as 10 min
- Measured
- sleep onset latency, sleep efficiency, self-rated sleep quality
- Result
- Water at 104-108.5 F (40-42.5 C) was associated with improved self-rated sleep quality and sleep efficiency, and when taken 1-2 h before bedtime for as little as 10 min with shorter sleep onset latency. Pooled effect sizes not stated in abstract.
- Limitations
- few studies; mostly healthy participants; water-based heating, not sauna
Efficacy of regular sauna bathing for chronic tension-type headache: a randomized controlled study.
Kanji G et al. J Altern Complement Med. 2015. PubMed 25636135 · DOI
- Who
- adults with chronic tension-type headache
- What
- regular sauna bathing plus advice vs advice alone
- Protocol
- 8 wk
- Measured
- sleep disturbance (secondary)
- Result
- No statistically significant improvement in sleep between sauna and control groups.
- Limitations
- sleep was a secondary outcome; participants not selected for insomnia
The Effect of Eight Weeks of Passive Heat Therapy on Mental Health, Sleep, and Chronic Pain in Persons with Spinal Cord Injury: A Pilot Study.
Uhlig-Reche H et al. J Clin Med. 2025. PubMed 40429561 · DOI · Free full text
- Who
- veterans with chronic spinal cord injury
- What
- supervised passive heat therapy raising oral temperature by 1 C (1.8 F) per session
- Protocol
- 8 wk
- Measured
- Epworth Sleepiness Scale (secondary)
- Result
- No improvement in sleep outcomes (p > 0.339).
- Limitations
- uncontrolled; n=10; daytime sleepiness rather than insomnia
Effects of passive body heating on body temperature and sleep regulation in the elderly: a systematic review.
Liao WC et al. Int J Nurs Stud. 2002. PubMed 12379298 · DOI
- Who
- 3 crossover studies of passive body heating in older adults, including healthy older women with insomnia
- What
- Warm bath immersed to mid-thorax, 104-105.8 F (40-41 C), 30 min in the evening
- Protocol
- 104-105.8 °F · 30 min
- Measured
- Body temperature rhythm and sleep
- Result
- Passive body heating raised rectal temperature, delayed the body-temperature nadir and increased slow-wave sleep in healthy older women with insomnia; participants perceived better sleep and quicker sleep onset after bathing.
- Limitations
- Only 3 small crossover studies, likely including the trials listed here; no pooled estimate.
Protocols used in the studies
Positive sleep studies used hot-water baths at 104-108.5 F (40-42.5 C) for 10-30 minutes, timed 1-2 hours before bedtime, over one to a few nights. No trial specifies an evening sauna protocol for insomnia.
What is still unknown
Whether evening sauna sessions improve sleep in diagnosed insomnia; comparison with first-line cognitive behavioral therapy for insomnia; durability with repeated use.
Safety
Cautions for sauna in this condition
- Older adults may experience orthostatic hypotension on rising after heat exposure, particularly on antihypertensive drugs (PMID 16871826).
- Evening heat exposure should end 1-2 hours before bedtime in the studied protocols; alcohol with sauna should be avoided (PMID 11165553).
- See general-safety.
For clinicians
Suggested rationale
Small studies (Dorsey 1996; Mishima 2005) and a meta-analysis (Haghayegh 2019) indicate that passive body heating by hot bath 1-2 hours before bedtime can improve sleep onset and continuity; sauna has not been tested in diagnosed insomnia, so any use would be an extrapolation of this mechanism.
Suggested wording only. The treating clinician decides whether it reflects their clinical judgment for this patient.
Typical ICD-10 codes: G47.00, F51.01. Examples only; the clinician assigns the code.
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