Air finds a gap. The pressure you were prescribed drops below what you were prescribed, the events it was holding open start creeping back, and at four in the morning you wake to a thin hiss beside your ear with one eye dried out. It is the most ordinary failure in CPAP and the one that ends the most therapies.
How to tell you are leaking
There are three signals, and it is common to have one without noticing the other two.
- A whistle or a hiss, usually louder at higher pressure and often only when you shift onto one side.
- A dry or irritated eye in the morning — air escaping upward at the nasal bridge goes straight at it.
- A raised leak figure on your machine's report, which is the one people miss, because a manufacturer app can show an otherwise cheerful night.
The fixes, in the order that works
Re-seat, do not tighten. This is the whole game. Cranking the straps deforms the cushion and pushes it out of its own seal, so the tighter mask leaks more than the loose one did. Loosen off, lift the mask clear of your face, settle it back down, and let the pressure inflate the cushion into place.
Then check the cushion for wear. Silicone hardens with use and a hardened cushion cannot seal against a moving face — most need replacing every one to three months, and the replacement is frequently the entire fix.
Then ask whether the mask suits how you sleep rather than how you lie still at a fitting. Side sleepers, people who move a lot, and people whose mouths fall open in the night often need a different style rather than a better fit of the wrong one.
If it persists past all of that, it is a clinic conversation — pressure and ramp settings are prescribed, and adjusting them is your sleep clinician's call, not an app's.
Where Nightshift helps
Tag the night as leaking and the pattern surfaces: which nights, at which point, after which change. A leak that only appears on the nights you sleep on your left is a different problem from one that arrived the week your cushion turned three months old, and the tag is what tells them apart.
Because a leak is also lost pressure, Nightshift lines the leak nights up against the figures — which is usually the moment someone realises their bad-numbers week and their leaking week were the same week.
Coaching only, not a diagnostic. Anything persistent belongs with your sleep clinician.