What does wake window mean?

The term comes up in two ways: as a schedule you build yourself (put baby down 2 hours after they wake up), and as a range a tracker estimates from age or from a baby's own sleep history. Neither one is exact. A wake window is a starting point, not a rule, and the right number for your baby can sit anywhere in the range below, or occasionally outside it.

Wake window by age

These are the age-based ranges Rhythm starts from before it has enough of a baby's own sleep history to use instead.

Age bands and minute ranges match Rhythm's own age-based defaults, used as the starting point before enough of a baby's own logged sleep is available.

Signs the window ran too long (overtired)

Watch for the baby getting more wound up instead of sleepier: eye rubbing, arching away from you, a sudden burst of energy right before what should be nap time, or crying that gets harder to settle the longer it goes on. An overtired put-down usually takes longer and the sleep that follows is often shorter and more broken than usual.

Signs the window was too short (undertired)

The opposite pattern: cheerful and playing right up to the moment you put them down, resisting the crib without obvious upset, or falling asleep quickly but waking again after a short nap. None of these are alarming on their own; they are just a signal to try stretching the window a little on the next cycle.

Why the window changes so fast

A newborn's nervous system tires quickly and the window is short and forgiving; there isn't much room to get it wrong. As a baby grows, the window widens and naps consolidate from many short ones down to two or one, which is why the same schedule that worked at 3 months usually stops working by 6.

Turning this into a schedule

The chart above doesn't know your baby's actual pattern yet. Rhythm's wake-window tracker starts from the same age-based range, then switches to your baby's own logged sleep once there is enough of it, and shows which of the two produced the number you're looking at.