DEEP BREATHING EXERCISES
Physiological Sigh: Instant Stress Relief
Calm down in 30 seconds with the double-inhale technique.
Last updated: January 6, 2026
Technique overview
What Is a Physiological Sigh?
A physiological sigh is your body's natural stress-relief mechanism—a double inhale followed by a long exhale. You do it instinctively when crying, yawning, or transitioning from sleep. Babies sigh about every 50 breaths to keep their lungs healthy. When done deliberately, this ancient reflex becomes a powerful tool: two quick inhales through the nose (the second a short 'top-up' to fill the upper lungs), then a slow, unforced exhale. Dr. Andrew Huberman popularized the controlled version on his podcast after Stanford research showed it outperforms meditation for rapid stress relief.
The Science Behind Physiological Sighing
When you breathe normally, some of your 500 million lung alveoli gradually collapse—reducing oxygen exchange and triggering stress signals. The double inhale of a physiological sigh reinflates these collapsed air sacs, maximizing lung surface area. Meanwhile, the extended exhale activates your vagus nerve, shifting your nervous system from fight-or-flight (sympathetic) to rest-and-digest (parasympathetic). This combination—mechanical lung reset plus neural calming—explains why one sigh can drop your heart rate and cortisol faster than any other breathing technique. The 2023 Stanford study (Balban et al.) found that just 5 minutes of daily cyclic sighing improved mood more than mindfulness meditation.
Benefits
Fastest relief during acute stress (1–3 cycles in seconds). Just as effective as meditation for mood when done daily. Naturally recruits your body's own calming reflex.
Physiological Sigh vs Box Breathing
Choose the physiological sigh when you need instant relief in 1-3 breaths—panic spikes, sudden anxiety, or stress that hits mid-conversation. It's invisible and takes only seconds. Choose box breathing when you have 2-5 minutes and want sustained focus or a structured practice—before presentations, during breaks, or as a daily routine. The sigh is a fire extinguisher; box breathing is climate control. For deepest calm, some practitioners start with 3 sighs to break acute stress, then transition to box breathing for extended downregulation.
Cyclic Sighing: The Clinical Term
In research papers and clinical settings, repeated physiological sighs are called 'cyclic sighing' or 'cyclic physiological sighing.' The 2023 Stanford study by Balban et al. used this term when comparing breathwork protocols to mindfulness meditation. Whether you call it physiological sighing, cyclic sighing, or the Huberman sigh—it's the same technique: double inhale, long exhale, repeat. The word 'cyclic' simply means you're doing multiple sighs in a row (2-5 minutes) rather than a single sigh for acute relief.
When to use
Stress spikes, before hard conversations, after startles. Or 2–5 minutes daily for mood. Fast, subtle, works anywhere—even in meetings.
When to skip
If dizzy or tingly, stop and try smaller, gentler breaths later. Avoid straining if pregnant, have cardiopulmonary disease, syncope history, or high blood pressure. If panic arises, pause and return when calm.
Step-by-step
How to practice
Structured walkthrough pulled from the editorial brief.
- Total time
- 30 seconds to 5 minutes
- Difficulty
- easy
- Tools
- Chair or comfortable seat, Optional on‑screen timer or haptics
- 1
Set posture
Sit tall. Jaw and shoulders relaxed. Breathe through the nose if possible.
10–15 seconds
- 2
First inhale
Inhale smoothly through the nose until the lower ribs expand.
~3–4 seconds
- 3
Top‑up inhale
Take a small second sip of air to gently fill the upper chest without shrugging.
~1–2 seconds
- 4
Long exhale
Exhale slowly through pursed lips (or nose) until comfortably empty.
6–10 seconds
- 5
Repeat as needed
Use 1–3 cycles for a quick reset; for training effects, repeat continuously.
2–5 minutes (optional)
Use cases
Where it fits
Situations where this breathing cadence excels.
Panic spike reset
Interrupt spiraling physiology with 1–3 cycles; longer exhales ease arousal quickly.
3 cycles, seated
Between‑meeting calm
Clear sympathetic carry‑over before a high‑stakes call.
60–120 seconds continuous sighing
Pre‑sleep settle
Downshift before lights out; keep breaths small and effortless.
2–3 minutes
Suggested frequency
As needed for acute stress (1–3 cycles); optional 2–5 minutes daily for mood and breathing‑rate changes
Practice notes
Keep it gentle
Helpful reminders so the pattern stays sustainable day after day.
Make the top‑up small
Let the second inhale gently fill the upper lungs without lifting the shoulders.
Exhale long, not forceful
Aim for 6–10 seconds. Feel empty enough to relax, not squeezed.
Shrink the breath if dizzy
Use smaller inhales, slower exhale, or pause. Comfort beats depth.
FAQ
Common questions
Evidence-backed answers we hear from practitioners most often.
What is the Huberman physiological sigh?
The physiological sigh popularized by Dr. Andrew Huberman on the Huberman Lab podcast is a natural stress-relief mechanism your body already uses. It consists of a double inhale (first through the nose to fill the lungs, then a second short sniff to top off), followed by a long exhale. Dr. Huberman explains that this technique was studied at Stanford and shown to be the fastest way to reduce stress in real-time. The 2023 Stanford study (Balban et al.) found cyclic sighing outperformed mindfulness meditation for mood improvement.
What evidence supports the physiological sigh?
A month‑long randomized study comparing three breathwork protocols to mindfulness found breathwork improved mood and reduced respiratory rate more, with the exhale‑focused cyclic sighing showing the largest gains. A pilot RCT in an orthopedic clinic waiting room found a 4‑minute cyclic‑sighing audio reduced pain intensity and unpleasantness vs. a time‑matched control. Together these suggest quick, modest benefits for mood and acute symptoms with brief daily practice.
How does a sigh help the lungs?
Sighs are deeper‑than‑normal breaths that periodically reinflate under‑ventilated lung regions, which helps prevent alveolar collapse and restores lung compliance. Neurophysiology studies identify a dedicated brainstem circuit (RTN/pFRG → preBötzinger complex) that can trigger sighs. That explains how they arise and why they increase under stress or hypoxia.
How many repetitions and how often?
For an in‑the‑moment reset, do 1–3 physiological sighs. For training effects, use 2–5 minutes of cyclic sighing most days. In the RCT, 5 minutes daily produced the clearest changes in mood and respiratory rate; a clinic pilot showed 4 minutes reduced pain. Start small and increase only if it stays comfortable.
Is it safe for everyone?
It's generally safe when done gently. Practice seated if you're prone to dizziness. People who are pregnant or have cardiopulmonary disease or syncope history should avoid straining and keep breaths small. Any light‑headedness likely reflects over‑breathing. Shrink the inhale and slow the exhale or stop and resume later.
Is the physiological sigh better than box breathing?
They're tools for different aims. The RCT found exhale‑focused cyclic sighing yielded the largest mood and respiration‑rate improvements vs. mindfulness, with box breathing also helpful. For rapid relief in a few breaths, many prefer sighing; for structured pacing or longer sessions, box breathing or coherent breathing may suit better.
How many physiological sighs should I do?
For an immediate reset during acute stress, 1-3 physiological sighs is usually enough—many people feel relief after just one. For a more sustained practice with training effects on mood and stress resilience, do continuous cyclic sighing for 2-5 minutes. The Stanford study used 5 minutes daily. Start with fewer repetitions and increase only if it feels comfortable.
Can I do a physiological sigh through my mouth?
Nasal breathing is preferred for both inhales because it filters, warms, and humidifies the air, and may enhance nitric oxide production. However, the technique still works with mouth breathing if nasal congestion makes nose breathing difficult. The exhale can be through pursed lips (like sighing 'ahh') or through the nose—whichever feels more natural and allows a longer, slower release.
Is cyclic sighing the same as physiological sigh?
Yes—cyclic sighing is the research term for repeatedly performing physiological sighs in sequence. A single physiological sigh is one double-inhale followed by a long exhale. Cyclic sighing strings these together for 2-5+ minutes as a structured practice. The Stanford study that compared breathwork to meditation used 'cyclic physiological sighing' as the formal name for this continuous practice.
What's the difference between a sigh and a physiological sigh?
A regular sigh is a single deep breath—typically one inhale followed by an exhale. A physiological sigh specifically involves TWO inhales: a full inhale followed by a short 'top-up' breath before the long exhale. This double inhale is what makes it physiological—it reinflates collapsed lung alveoli and triggers a stronger parasympathetic (calming) response than a regular sigh. Your body does this naturally about every 5 minutes, but doing it deliberately amplifies the stress-relief effect.
Watch & learn
Dr. Andrew Huberman Explains the Physiological Sigh
Stanford neuroscientist Dr. Andrew Huberman demonstrates and explains the physiological sigh—the fastest way to reduce stress in real-time.
Research & safety
What evidence says
Peer-reviewed highlights and guardrails pulled from the content brief.
Study highlights
Balban et al., 2023 - Cell Reports Medicine (RCT)
Remote 4‑arm randomized study (5 min/day for 28 days): breathwork > mindfulness on mood and respiratory‑rate change; exhale‑focused cyclic sighing largest gains.
Hanley et al., 2025 - Journal of Behavioral Medicine (pilot RCT)
4‑minute cyclic‑sighing audio in an orthopedic clinic waiting room reduced pain intensity and unpleasantness vs. control.
Severs, Vlemincx, Ramirez, 2022 - Biological Psychology (Review)
Sighs maintain lung compliance by preventing alveolar collapse; frequency increases with stress/hypoxia; preBötzinger complex involvement.
Li et al., 2016 - Nature (Mechanism)
Identified peptidergic RTN/pFRG → preBötzinger circuit controlling sigh generation; sighs re‑inflate alveoli and may preserve lung integrity.
Safety notes
- Stop if dizzy, tingly, or chest‑tight; resume later with smaller breaths.
- Practice seated if prone to light‑headedness or syncope.
- Pregnancy: avoid straining; no prolonged breath holds required.
- Cardiopulmonary disease or uncontrolled hypertension: gentle pacing; consult a clinician if unsure.
Use case guides
Related patterns
Quick sessions
Short on time? Try a timed session: