Nattra reads last night, tells you the one thing worth doing before bed, and never pretends to know more than it does.
Each night is a star at its own height, brighter the longer you slept. The band of dust is your need — a range, never a single number. Only last night is ever marked amber.
Under ten seconds, or let Apple Health fill it in. Guessing is fine — we count it as ± 30 min.
One thing, like "in bed by 10:15" — never a list of habits to fail at.
Sleep debt and wake-time consistency, each drawn with the range the data actually supports.
One number claims precision your sleep data doesn't have.
Not measurable from a wrist or a phone, and weakly tied to how your day goes.
The 90-minute wake window isn't backed by evidence.
Trying harder to sleep makes sleep worse. One rough night breaks nothing.
If you lie awake despite plenty of time in bed, Calm Mode switches off sleep debt entirely and coaches only a steady wake time and a gentle wind-down.
It also points you to CBT-I, the first-line treatment for insomnia — starting with free programmes from the US VA. Calm Mode is never behind a paywall.
No account, no analytics, no server. Your sleep stays on your iPhone, and Apple Health is read for sleep only.