Nap times go awry when we miss our “sleep window” — that magic snippet of time in which baby is primed for “la la land” and will drift off peacefully (in the right environment). Perhaps you’ve seen your baby’s sleep window open — a glazed look, a yawn, or some agitated movements (depending on age) — but by the time you finished that bite of food, changed the diaper, and swaddled, that window had slammed shut on you! One missed window can set in motion a vicious cycle of overtiredness, short naps and more disturbed night sleep. Going by a strict schedule can be problematic too, because every night and every nap is different, (particularly in the first six months). You usually end up with a baby who’s overtired or undertired at the “scheduled” sleep time.

So should you watch the baby (for signs of sleepiness) or watch the clock in order to put baby to sleep during her sleep window? The answer is, both! Here’s how: The heart of consistently successful “sleep window synchrony” (my term) is staying within an optimum wake time. Wake time is the duration of wakefulness between sleep times, counting the time it takes to soothe your baby to sleep.

Simply put, wake time is the single most powerful determinant of when your baby will need to sleep again! Knowing the best wake time will help you stay ahead of overtired like nothing else, because you’ll be ahead of those tricky sleepy cues too (some babies are just hard to read!).

Below, exclusively for The Baby Sleep Site®, I’ve outlined my secret formulas for knowing when baby’s “wake time” is going to expire. The formulas vary by age, so look for your baby’s age range to know which number to start with, then “tweak it” with the factors that follow, and you’ll have a nearly exact predictor of when your baby next needs to snooze. (You should still keep logs to optimize for individual differences until you’ve got it down.)

Here’s why these formulas are proven golden in avoiding Healthy Sleep Enemy #1, overtiredness: They factor in the second most powerful determinant of when baby needs sleep — duration of the last sleep time. Since babies through at least six or seven months normally have erratic sleep durations — some naps last 20 minutes, some 2 hours — we have to factor in duration or we’re shooting in the dark for that critical sleep window.

I discovered with my little one, and later through consulting for other mommies, that for young babies (particularly zero to four months), the duration of the previous sleep time predicts the next wake time! After around six months, baby should be taking the full (one-hour-minimum) naps anyway, so we can look more to the age-determined wake times (though duration can still be a factor).

The Wake Time Formulas

0 to 1 month – Wake time = Duration of the last sleep time, up to 40 minutes max.

Newborns are rarely awake longer than it takes them to feed and have a diaper change. If they don’t doze back quickly, they need our help to make sleep happen on time! Of course, if baby goes to sleep sooner, don’t try to keep a newborn awake for the full 40 minutes.

*Note: During what is often called, “the witching hour” (or in my case, full blown colic time) many newborns simply will not sleep for hours on end, despite your best soothing efforts. This doesn’t mean they don’t need to! This is the time to really take Nicole’s sleep-inducing tips to heart. Diligence pays and every bit of extra sleep you get out of baby during this time will help in the big picture, even in the long run, after colic has passed.

1 to 2 months – Wake time = Duration of the last sleep time up to max, 40 to 60 minutes.

During these months, the best rule of thumb is the duration of the last nap, since nap length is biologically a work in progress for babies at this stage. Plan to put back to sleep within one hour of wakefulness (or less if last sleep period was less). Lean closer to 40 minutes for colicky/sensitive babies, especially during the morning hours. (Also see “witching hour” note above.)

2 to 3 months – Wake time = Duration of the last sleep time up to max, 60 to 80 minutes.

At this age, if baby sleeps less than 45 minutes, you should immediately try to continue the nap (by rocking, soothing, etc.) to equal at least 45 minutes, but if your attempts are unsuccessful (as they often will be), simply calculate wake time by the sleep duration, instead of max time.

3 to 4 months – Wake time = Duration of the last sleep time up to max, 60 to 90 minutes.

Yawn or no yawn …cranky or not…. At 50 minutes or so (depending on tweaking factors below), begin your nap time wind down routine, aiming to have baby asleep within this range.

4 to 6 months: Wake time = Duration of the last sleep time up to max, 1 hour 15 minutes to 1 hour and 45 minutes.

Baby usually has developed three somewhat predictable naps, but the wake time is still a more important indicator of the sleep window, than the “scheduled” nap.

6-8 months: Look for wakeful periods to begin to stretch to 2.5 hours without becoming overtired, provided that the naps are not too short.

Nap duration is less of a factor now. The first nap of the day will still need to occur a bit earlier (within 2 hours).

*Note: Activity level now becomes a factor, because many babies are mobile. If your little one has had a very active wake time, you may need to tweak in the earlier direction 10 minutes or so.

8-10 months: Wake time – 2 to 3.5 hours.

For the first two naps, wake time should be between 2 and 2.5 hours, so you’re starting with just one three hour period of wakefulness per day (the one before bedtime). This range depends greatly on whether baby has dropped the third nap (usually at 9 months). Generally, thereafter, the 3.5 hour wake time works (from the time baby drops the third nap) until baby drops the second nap between 14 and 18 months (approximately).

Tweak It Factors

Now that you know the range to shoot for, here’s how you can hone in on a more precise prediction of the infamous closing sleep window.

• Time of day: As noted above, the morning nap usually will still need to happen at the early end of the given range. The later time given applies to the longer period of wakefulness in the late afternoon/early evening.
• Temperament/Colic or post-Colic: With colicky babies, always go with the shorter wake time and keep a log to pinpoint even further. Once colic has passed, at around 3 months for most babies, these sensitive little ones still need this shorter wake time, especially in the morning. The same applies to babies who are sensitive to over-stimulation (but may not be considered “colicky).
• Quality and quantity of night sleep: Usually, if baby has a bad night, he will close his sleep deficient with the length of his nap, but it’s worth checking out Nicole’s night sleep totals and if your baby gets less night sleep and takes a short nap, move that wake time back to the shorter end.

Every baby is different, but the vast majority will fall within these ranges. (Most babies are also chronically overtired!)

This wake time formula is the clock-watching part of knowing when to facilitate baby’s next nap, but it’s the antithesis of rigid scheduling. It gives you a starting point from which to log what works best for your baby, as regular naps develop.

This was a guest article by Angela Braden. Angela Braden is mother of Kian, 5, and Gianna, 17 months. She has researched and reported on wellness and lifestyle for a decade and a half and been published hundreds of times in national and international magazines such as Harper’s Bazaar, Women’s Health and Fitness, and Lucire (New Zealand). Angela served as a columnist and healthy lifestyle expert on TBS for 2 years. She swears her two babies are angels…but only when they’ve had optimum sleep.

©2012 by Angela Braden. All rights reserved. No part of this document may be reproduced or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission of Angela Braden.

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