What time should a baby go to bed?

Between 19:00 and 20:30 is the most common answer from four months on, but the right hour is the one your household can keep to every day. Regularity matters more than the number.

Should bedtime be pushed later if they napped badly?

The opposite usually works: bring it forward a little. A day with little nap arrives with more sleep debt, and stretching the night to «make up for it» normally turns out worse.

Bedtime: why it is not calculated, it is measured

If you add up wake windows from the moment they get up, bedtime comes out of the chain and moves with it: one long nap shifts dinner, the bath and the night. In real life that is not what happens.

The night is set by the household, not by the sum

In almost every house the night falls at the same time almost every day, because around it there is a dinner, a bath and parents who would also like to go to bed.

napnap treats it that way: bedtime is the median of the last two weeks of recorded nights, and it does not drag when a nap runs long. If there are no nights recorded yet, it uses the hour you put in settings.

Median and not mean, and the reason is specific

In a house where the four-in-the-morning waking sometimes gets recorded as two sleeps, half a dozen split nights drag a mean and do not move a median.

The same goes for how long the night lasts: it is measured with the median of the last ten, and separately from the naps. Measuring a night against the average of the naps is what made an app announce at four in the morning that they were long overdue.

And that is why its margin is different

When a future day is forecast, each nap carries the uncertainty of the morning plus that of every window before it: the third is known less well than the first.

The night is not like that. Being anchored to the clock, it carries its own margin and not the accumulated one — which is the difference between telling you «bed around 20:00 ± 20 min» and «± 3 h», which says nothing at all.

Questions

What time should a baby go to bed?: Between 19:00 and 20:30 is the most common answer from four months on, but the right hour is the one your household can keep to every day. Regularity matters more than the number.
Should bedtime be pushed later if they napped badly?: The opposite usually works: bring it forward a little. A day with little nap arrives with more sleep debt, and stretching the night to «make up for it» normally turns out worse.