Science-backed · Navy SEALs · Stanford · Sleep Research
Stillsea is a free collection of guided breathing exercises built on techniques backed by research from Stanford, clinical sleep studies, and high-performance training programs. Each exercise runs as an interactive timer right in your browser — no app to download, no account to create.
Tell us how you feel and we recommend a technique, or explore the exercises below and choose your own.
4-4-4-4 technique used by Navy SEALs for calm and focus.
Start exercise → SleepExtended exhale pattern designed to help you fall asleep faster.
Start exercise → Balance & HRVSimple 5-5 rhythm to balance your nervous system and boost HRV.
Start exercise →Choose your mood. Pick how you feel — anxious, sleepless, unfocused, low energy, or tense — and Stillsea recommends the right technique.
Follow the guided timer. An animated visual guides each inhale, hold, and exhale so you can close your eyes and simply breathe.
Feel the shift. Most people notice a calmer mind and slower heart rate within one to two minutes — about four rounds of breathing.
Yes. Slow, controlled breathing activates the parasympathetic nervous system — the body's "rest and digest" mode — which lowers heart rate, reduces cortisol, and eases the physical symptoms of stress. Research from Stanford, Harvard, and clinical studies consistently shows measurable effects within just a few minutes of practice.
If you are new to breathwork, box breathing (4-4-4-4) is the easiest to learn because every phase is the same length. For sleep, try the 4-7-8 technique. For general daily balance, coherence breathing (5-5) is a great choice. You can also let Stillsea recommend one — just pick how you feel on the homepage.
Most people feel calmer after just one to two minutes (about four rounds). For deeper relaxation or to build long-term resilience, aim for five to ten minutes daily. Consistency matters more than session length.
Yes, completely free. All breathing exercises and guided timers on Stillsea are available at no cost with no sign-up required. Open the page and start breathing.
Breathing exercises are generally safe for most people. However, if you have a respiratory or cardiovascular condition, are pregnant, or experience dizziness during practice, stop and consult a healthcare professional. These exercises are not a substitute for medical advice or treatment.