What a wake window is
A wake window is the stretch of time your baby is awake between two sleeps. Too short, and they are not tired enough to settle. Too long, and they tip into overtired: harder to settle, shorter naps, more night waking. The sweet spot sits in between, and it is different for every baby and for every nap of the day.
Where the first schedule comes from
On day one Sleep Gem has no history, so it starts from age-appropriate defaults: the awake times that suit most babies of your child’s age. If you already know your baby’s windows, enter them yourself with Optimise Myself. Either way, you get a usable put-down time from the first nap.
How it learns
With Optimise For Me switched on, Sleep Gem re-reads your logs at the end of every day. For each nap slot it looks at how long your baby was awake beforehand, how long they slept, and how quickly they settled, and moves the window toward what worked.
- Per nap. The first nap of the day and the last are different problems, so each slot is learned separately.
- Recent days weigh more. A recency-weighted estimate means growth spurts, teething and nap transitions show up in days, not weeks, while a single odd day cannot drag the schedule around.
- Small data, handled honestly. With only a couple of observations the estimate stays close to the age defaults, then shifts toward your baby’s own pattern as evidence builds. The app tells you when it is still learning a slot.
- Interrupted naps count once. A nap that breaks and resumes is treated as one sleep opportunity, not two, so it cannot fool the model into thinking your baby needs a much shorter window.
- Sick days are set aside. Mark a day as unwell and it is excluded from learning.
What you log
Two taps per sleep are enough: Sleep when your baby falls asleep, Wake Up when they wake. If you also log Put Down and Pick Up, Sleep Gem tracks how long settling takes and uses it to fine-tune the timing. Made a mistake? Undo it, edit the time, or insert a missed entry between two others. At the end of the day, tap End Day and answer a couple of questions about the night. That is the whole routine.
Prefer not to log at all? In early access, connect a compatible Wi‑Fi baby monitor and Sleep Gem watches for the four moments that matter, put-down, asleep, awake and pick-up, and records them for you. It is the same log, filled in automatically, and you can correct any entry as usual. Automatic logging is being rolled out gradually; email us to join.
The put-down moment
Through the day the home screen shows one number that matters: the time to put your baby down for the next sleep. It counts down as the wake window fills, updates if a nap runs short or long, and comes with a plain-language reason. It is a guide, not a deadline: if your baby shows sleepy signs earlier, follow your baby.
Bedtime
Bedtime is not a fixed clock time. Sleep Gem works it out from the total awake time your baby has had that day and from how their nights have gone, so a day with a short last nap gets an earlier bedtime and a day with a late nap gets a later one. Night wakings and early rises are read in the morning briefing and feed back into the plan.
Nap transitions
Dropping from three naps to two, or two to one, is the hardest week in baby sleep. Sleep Gem notices when a nap keeps failing to happen, plans the day around the new count when that is what the day calls for, and keeps your baby’s usual routine in memory so a one-off day does not become the new normal.
The evidence
We test the timing engine the way you would want us to: against real logs, scored on what happened next. In our backtest over 251,000 nap decisions, timing learned from the baby’s own logs beat a fixed age-band table at every age we could score, and the gap widened as babies grew: roughly level at two to three months, and by the toddler years the table’s timing error was about two and a half times ours, when individual differences are largest.
Backtest of the production engine against a static age-band wake-window table, July 2026, scored by absolute error between predicted and observed nap onset. Results describe our engine’s behaviour on our users’ historical logs; they are not a clinical trial and are not a promise about any individual baby.
What Sleep Gem is not
- It is not medical advice and not a medical device. For anything about your child’s health, feeding, breathing or development, talk to your paediatrician.
- It is not a sleep-training method. It tells you when, not how.
- It will not fix a schedule you do not log. The first days of logging matter most.
