Does Hyperbaric Oxygen Therapy Make You Tired? Here’s What Science Says

The Surprising Link Between HBOT and Fatigue

Hyperbaric Oxygen Therapy (HBOT) is widely recognized for its ability to accelerate healing, reduce inflammation, and improve cognitive function. But a common question patients ask is: Does Hyperbaric Oxygen Therapy Make You Tired? The short answer is yes—at least for some individuals. This fatigue, however, is often a sign that your body is working intensely to repair itself. Understanding the science behind this phenomenon can help you optimize your sessions and set realistic expectations.

When you undergo HBOT, you breathe in 100% oxygen under increased atmospheric pressure. This forces oxygen to dissolve directly into your plasma, reaching tissues that normally lack sufficient oxygen. As a result, your cells undergo a surge in metabolic activity—much like a boost to your internal “engine.” This heightened state of repair can temporarily drain your energy reserves, leading to post-session tiredness. Think of it as the body’s natural response to intensive healing, similar to how you might feel exhausted after a vigorous workout.

Immediate vs. Long-Term Energy Effects

Immediate fatigue after HBOT is often short-lived, lasting anywhere from a few hours to the remainder of the day. For some, this post-therapy drowsiness mirrors the effects of a long, deep sleep—refreshing yet momentarily draining. In contrast, long-term users may experience chronic fatigue-like symptoms if sessions are too frequent or if underlying conditions (e.g., chronic inflammation or mitochondrial dysfunction) persist. However, as your body adapts, many patients report a net increase in energy levels over weeks or months, as HBOT reduces oxidative stress and improves cellular efficiency.

Another key factor is the role of the parasympathetic nervous system. During treatment, the pressurized environment can lower cortisol levels (stress hormone) and promote relaxation. This “rest-and-digest” state naturally brings on a sense of calm or sleepiness. So, while the question Does Hyperbaric Oxygen Therapy Make You Tired may seem straightforward, the answer depends on individual health status, session duration, and overall oxygen dosage.

Why Fatigue Can Be a Positive Sign

For many patients, feeling tired after HBOT is actually a tip-of-the-iceberg indicator of healing. When tissues with low oxygen levels suddenly receive a flood of oxygen, the body initiates a cascade of repair processes: stem cell mobilization, collagen synthesis, and blood vessel formation. These processes require significant energy, drawing on your body’s ATP (adenosine triphosphate) reserves. The temporary energy deficit is similar to expecting to feel energized after a marathon—but your body will gradually recover stronger as the infrastructure improves.

Clinical studies also show that HBOT can reduce brain fog and mental fatigue in patients with traumatic brain injuries or long COVID. Paradoxically, this improvement often begins with a feeling of physical exhaustion during the early sessions. So, if you feel worn out after your first session, don’t be alarmed—this could be a sign that the therapy is effectively stimulating systemic repair. The key is to stay consistent and listen to your body’s recovery signals.

How to Manage Post-HBOT Fatigue

Strategies to mitigate afternoon drowsiness include scheduling sessions early in the day, maintaining optimal hydration (since dehydrated cells work harder), and combining HBOT with adequate sleep. A light, nutrient-dense snack before treatment—like a banana or almonds—can also stabilize blood sugar levels and reduce post-therapy crashes. Additionally, avoid heavy meals or caffeine immediately before sessions, as these can conflict with oxygen uptake and