How to work out your baby's average wake windows from a sleep log

"How long is my baby awake between sleeps?" is one of the most useful questions a sleep log can answer. Here's how to work it out properly, by hand or in a spreadsheet.

What a wake window is

A wake window is the time your baby is awake between one sleep and the next. It starts when a nap or the night ends and stops when the next sleep begins. The first wake window of the day runs from the morning wake-up to the first nap, and the last runs from the final nap to bedtime.

Wake windows vary between babies, between ages, and from one day to the next. Published charts of typical wake windows by age don't all agree. That's why looking at your own baby's recent pattern can be more useful than a chart. For what's typical at your baby's age, your pediatrician is the right person to ask.

The method in four steps

1. List the sleeps in time order. Every nap and every night sleep, with start and end times.
2. Measure each gap. Gap = the next sleep's start minus this sleep's end.
3. Leave out what isn't really a wake window. More on this below.
4. Average the gaps. Add them up and divide by how many there are.

A worked example

Here's one made-up day:

Total: 140 + 150 + 150 + 135 = 575 minutes. There are 4 wake windows, so 575 ÷ 4 ≈ 144 minutes. The average is about 2h 24m.

Working in minutes makes the arithmetic much easier. Convert back to hours and minutes at the end: 144 minutes is 2 hours (120) plus 24 minutes.

For a weekly average, pool every wake window from the seven days and average them all together, rather than averaging seven daily averages. Days with more naps then count in proportion to how many wake windows they had.

What to leave out

Night wakings

Say your baby went down at 7:20pm, woke at 11:30pm, and was back asleep by 11:50pm. That 20-minute gap is a night waking, not a wake window. If you count it, it pulls the average down a lot and stops it meaning anything. WakeGlance ignores gaps between two parts of the same night.

Gaps from missed logs

Everyone forgets to log a nap sometimes. When that happens, the log shows a huge gap, maybe eight or ten hours, that never really happened. WakeGlance skips any gap longer than 10 hours for this reason. If you're doing it by hand, look for gaps that seem impossible and leave them out.

Overlaps and duplicates

Two caregivers sometimes log the same nap, or a sleep is stopped and restarted a minute later. Join sleeps that overlap or touch into one, and delete exact duplicates, before measuring gaps.

Rough days

Teething, illness, travel and vaccine days can look very different from usual. It's reasonable to leave them out when you want to see the normal pattern. In WakeGlance you can flag those days and they're left out of the averages.

Telling naps from night sleep

Most logs don't label sleeps as naps or nights, so you need a rule. A simple one: a sleep is night sleep if it starts in the evening or overnight, or if it's very long. WakeGlance's default is a start between 6pm and 6am, or 4 hours or more, and both can be changed. This matters for leaving out night wakings and for counting naps per day.

Doing it in a spreadsheet

1. Open your CSV export, filter Type to Sleep, and sort by Start.
2. In a new column, subtract each row's End from the next row's Start. Format the result as a duration.
3. Delete gaps that are night wakings, gaps over 10 hours, and negative or zero gaps from overlaps.
4. Use an AVERAGE formula on what's left.

It works, but it takes a while, and you have to redo it every time you want a fresh number.

Comparing this week with last week

One day's average jumps around. A weekly figure is steadier, and comparing it with the previous week shows whether something is actually shifting. Use complete days only, since today isn't finished yet. WakeGlance takes your last seven complete days and the seven before them, and only compares once a week has at least three days in it.

Let WakeGlance do the counting

WakeGlance applies all of the above to your whole log in a few seconds, right in your browser. It shows "awake stretches averaged 2h 24m this week, vs 2h 30m the week before"-style sentences, awake time per day, naps per day and the longest night stretch. It also makes a one-page summary for your pediatrician. Nothing is uploaded.