Most sleep apps assume you go to bed at 10pm. Steady doesn't. Tell it your shift pattern once (pick from 9 prebuilt templates: 4 on / 4 off, Panama 2-2-3, DuPont, fixed nights, on-call, or build your own) and every part of the app calibrates to your real schedule.

The Fatigue Score is a 0 to 10 number that combines your cumulative sleep deficit, hours awake, body clock dip, and last shift type. Tap any score to see exactly what's driving it. The Smart Nap Planner suggests a 20 minute power nap window timed to your afternoon dip, with an optional reminder 15 minutes before, and a 3 day fatigue forecast shows you which of your upcoming shifts is going to hurt before you get there.

The feature I care most about is the drive-home risk alert. When your fatigue crosses the line, Steady tells you plainly what your impairment is roughly equivalent to in blood alcohol terms, because most people have no intuition for how dangerous a drive home after a third night shift actually is. There is also a smart wake alarm that finds the lightest moment inside a 30 minute window instead of tearing you out of deep sleep at a fixed time.

Log sleep manually in 5 seconds or auto pull from Apple Health (Apple Watch and iPhone), with both sources merged without duplicates. The Shift Calendar gives you a month view color coded by phase (day, evening, night) with one tap overrides for sick days, swaps, and mandatory overtime. Stats overlay sleep against shift type so you can see the pattern.

Bilingual EN and ES, written by Spanish speakers, not machine translated. Over 300 coaching tips are grounded in AASM, NIOSH, and chronobiology research, and searchable in both languages. No server, no account, your data never leaves your iPhone, and the App Store privacy label reads Data Not Collected. Steady Pro is $3.99 a month or $24.99 a year, with a 7 day free trial on the annual plan.