Low vs. High Pressure HBOT: What the Research Reveals About 1.5 ATA

For decades, hyperbaric oxygen therapy (HBOT) has been synonymous with high-pressure chambers operating at 2.0-3.0 atmospheres absolute (ATA). However, a growing body of evidence shows that mild hyperbaric therapy at 1.5 ATA may offer comparable benefits for numerous conditions, with improved accessibility, safety, and patient comfort.

Traditional HBOT typically operates at 2.0-3.0 ATA with 100% oxygen, while mild HBOT uses 1.3-1.5 ATA. This seemingly modest difference has significant implications for treatment accessibility and compliance, yet research increasingly shows that lower pressures can achieve therapeutic outcomes across multiple domains.

One of the most exciting developments in HBOT research involves its effects on cellular aging. A landmark study published in the peer-reviewed journal Aging demonstrated that HBOT can increase telomere length by over 20% and significantly reduce senescent cells in healthy aging adults. The study used 60 daily sessions at 2.0 ATA, but importantly, research indicates that neurologic benefits are often optimized between 1.3-1.75 ATA, as the brain is particularly sensitive to oxygen and pressure. The implications are profound: telomere length in immune cells increased by 25-37%, while senescent T helper cells decreased by 37%, changes that lifestyle interventions typically achieve at only 2-5%. This represents the first human study demonstrating cellular-level age reversal through a non-pharmacological intervention.

Mild HBOT is regularly used for wound healing. For diabetic foot ulcers, one of HBOT’s most established indications, clinical guidelines from the Underwater and Hyperbaric Medical Society indicate that pressures of 1.4 ATA are required for therapeutic effect. A comprehensive meta-analysis of 14 studies involving 768 participants showed that HBOT significantly improved complete healing of diabetic foot ulcers and reduced major amputation rates. For wound healing, consistency and adequate tissue oxygenation matter more than maximum pressure. While 1.5 ATA meets the therapeutic threshold, protocols between 1.4-2.5 ATA have all shown efficacy depending on session duration and frequency.

Sleep disturbances affect millions, and HBOT shows promise as an adjunctive therapy. A randomized trial of patients with chronic insomnia at high altitude found that a 10-day HBOT course significantly improved both Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index (ISI) scores. In military personnel with mild traumatic brain injury, HBOT at 1.5 ATA improved five out of eight PSQI sleep measures at 13 weeks and two out of eight at six months. The mechanisms appear multifactorial: enhanced cerebral oxygen metabolism, reduced inflammation, and support for the brain’s glymphatic system—the “waste clearance” mechanism that activates during deep sleep. Research on children with cerebral palsy showed that total sleep items improved significantly after 10 and 20 HBOT sessions, with therapy proving both safe and effective.

The evidence for mild HBOT in autism is also compelling. A multicenter, double-blind study using 1.3 ATA with 24% oxygen for 40 sessions showed that physician CGI scores significantly improved in overall functioning, receptive language, social interaction, eye contact, and sensory/cognitive awareness compared to slightly pressurized room air. Studies using HBOT at pressures up to 1.5 ATA with 100% oxygen have been reported as safe and well-tolerated, with decreased inflammation markers measured by CRP levels.

Elite athletes are increasingly turning to mild HBOT for recovery optimization. Olympic athletes at the Nagano Winter Olympics received HBOT at 1.3 ATA for 30-40 minutes with a maximum of six treatments, and all athletes reported faster recovery rates. The lower pressure was sufficient to accelerate lactate and ammonia clearance. A study on Chinese secondary national-level athletes using mild HBOT at 1.25 ATA with 26-28% oxygen showed reduced subjective fatigue and improved recovery markers compared to controls. For athletes, mild protocols (1.3-1.5 ATA) appear effective for recovery between training sessions, while higher pressures may be reserved for serious injuries or intensive recovery periods.

Perhaps the most visible benefits of HBOT appear in skin health and aging. A prospective clinical trial demonstrated that 60 daily HBOT sessions in elderly patients increased collagen density, elastic fiber length, and blood vessel numbers while decreasing senescent cells and papillary dermis thickness. These weren’t superficial changes, tissue biopsies confirmed improvements at the cellular level. Collagen fiber density increased significantly with a large effect size, while elastic fiber length increased by nearly three times the baseline variation. The mechanisms are well-understood: oxygen is essential for collagen synthesis, and increased tissue oxygenation stimulates fibroblast activity, the cells responsible for producing structural proteins. Regular HBOT treatments increase skin elasticity and stimulate collagen production, leading to reduction of wrinkles and fine lines and improvement in skin texture. Many dermatology clinics now integrate mild HBOT protocols (1.3-1.5 ATA) as complementary therapy alongside topical treatments, offering patients a “from-within” approach to skin rejuvenation.

The future of HBOT lies not in a one-size-fits-all approach but in matching pressure, oxygen concentration, and session frequency to individual conditions and patient needs. Mild HBOT represents a democratization of this powerful therapy, making it more accessible, affordable, and practical for long-term use.

As research continues to validate the efficacy of lower-pressure protocols, we may see a paradigm shift: from viewing HBOT exclusively as an acute medical intervention to recognizing it as a versatile tool for optimization, prevention, and regenerative medicine.

References:

1. Telomere Lengthening Study: Hachmo Y, Hadanny A, Abu Hamed R, et al. Hyperbaric oxygen therapy increases telomere length and decreases immunosenescence in isolated blood cells: a prospective trial. Aging. 2020;12(22):22445-22456.

    

   https://pubmed.ncbi.nlm.nih.gov/33206062/

    

2. Cell-Level Aging Reversal: ScienceDaily. Hyperbaric oxygen treatment: Clinical trial reverses two biological processes associated with aging in human cells. November 2020.

    

   https://www.sciencedaily.com/releases/2020/11/201120150728.htm

    

1. Diabetic Foot Ulcer Meta-Analysis: Efficacy of hyperbaric oxygen therapy for diabetic foot ulcer, a systematic review and meta-analysis of controlled clinical trials. Scientific Reports. 2021;11:2788.

    

   https://www.nature.com/articles/s41598-021-81886-1

    

2. UHMS Clinical Guidelines: Underwater and Hyperbaric Medical Society guidelines indicate pressures of at least 1.4 ATA are required for therapeutic effect in diabetic foot ulcers.

1. Multicenter Double-Blind Study: Rossignol DA, et al. Hyperbaric treatment for children with autism: a multicenter, randomized, double-blind, controlled trial. BMC Pediatrics. 2009;9:21.

    

   https://bmcpediatr.biomedcentral.com/articles/10.1186/1471-2431-9-21

    

1. Mitochondrial Biogenesis Study: Hadanny A, Hachmo Y, Rozali D, et al. Effects of Hyperbaric Oxygen Therapy on Mitochondrial Respiration and Physical Performance in Middle-Aged Athletes: A Blinded, Randomized Controlled Trial. Sports Medicine Open. 2022;8(1):22.

    

   https://sportsmedicine-open.springeropen.com/articles/10.1186/s40798-021-00403-w

    

2. PubMed Reference: Effects of Hyperbaric Oxygen Therapy on Mitochondrial Respiration and Physical Performance in Middle-Aged Athletes.

    

   https://pubmed.ncbi.nlm.nih.gov/35133516/

    

1. PubMed Skin Study: The effect of hyperbaric oxygen therapy on the pathophysiology of skin aging.

    

   https://pmc.ncbi.nlm.nih.gov/articles/PMC8660605/

    

1. HBOT for mTBI Post Concussion: Harch PG, et al. Hyperbaric oxygen therapy for mild traumatic brain injury persistent postconcussion syndrome: a randomized controlled trial. Medical Gas Research. 2020.

    

   https://hbot.com/hbot-for-mtbi-post-concussion-syndrom-randomized-controlled-trial/

    

This article is for informational purposes only and does not constitute medical advice. Always consult with qualified healthcare professionals before beginning any hyperbaric oxygen therapy protocol.