Exclusive Wake-Time Formula – Your Missing Link For Great Baby Sleep

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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147 thoughts on “Exclusive Wake-Time Formula – Your Missing Link For Great Baby Sleep”

  1. My son will be 6 months in 5 days and is still taking between 3-4 naps a day. His first wake window is 1.5 hours, but he only naps for about 30 minutes. Sometimes he wakes up happy and sometimes he wakes fussy. His wake windows after that are usually 1.5-1.75. I feel like his wake times need to be longer, but he acts so sleepy that I think he’ll be overtired if I try to extend his wake times. What should I do?

    • Hi Victoria,
      Thank you so much for your comment! I’m so sorry to hear you’re struggling with naps – you’re definitely not alone! This is a tough age. It’s really hard to know what’s going on here without asking a lot more questions, and maybe getting a sleep log. You may want to talk with a sleep consultant to make a plan to lengthen naps and wake time. Or, have you seen our free nap ebook? It might be able to help you troubleshoot: https://www.babysleepsite.com/free-baby-nap-guide/
      Best of luck!

  2. Hi just a question in regards to this formula- my daughter is 19weeks and still has very erratic nap times some are 30min some (very rarely) are 1.5hrs, majority are however 40-45 mins.

    Using your formula does this mean that if she only has a 30min nap her awake time is only 30mins?? Or is her awake time 1hr and 15 mins with a max limit of 1hr 45. Sorry I’m just a little confused.

  3. What do I do if my baby misses her last nap? She’s 5 months, and seems to have 2-hour wake windows most of the time. Occasionally she can’t fall asleep for her last nap, and then I don’t know what to do. I don’t want her to get extremely overtired so I usually end up putting her to sleep for the night very early (about an hour after the nap was supposed to happen but didn’t). But I’m not sure if I should be putting her to bed at 6 pm if most other nights she’s in bed between 7 and 8:30.

    • Hi Anna,
      Thank you for your comment! Generally, if your baby is missing her last nap only occasionally, putting her to bed early on those nights is fine, as it will prevent overtiredness and maintain good sleep for her. If she’s missing her last nap often, though, then there might be scheduling problem, where the last nap is just too close to an earlier nap or to bedtime. We have a sample 5 month-old schedule here that you can compare with what you’re doing at home, to see if that might be the issue: https://www.babysleepsite.com/schedules/5-month-old-baby-schedule/

      I hope this helps, but please let me know if you have any questions!

      • Hi! I checked your sample schedule – and also your 6 month schedule since she just turned 6 months today. I’m basically trying to do the exact thing with sleep that your schedule says, and it works for the first two naps – she falls asleep after being awake somewhere between 2 and 2:15. But today is the third day in a row where she’s fighting her third nap – for the past two days she wouldn’t take it at all. I ended up keeping her up for 4 hours which I hate to do, and putting her to bed at 6 instead of at 7. I’m not sure what’s going wrong at all.

      • Hi @Anna, thank you for writing to us. I’ve struggled before with the catnap too so I know how frustrating that is! I found on days I knew my baby really needed the sleep but was resisting it that wearing him for that last nap, or going on a walk in the stroller could get us through, but I also agree with your idea to just bring bedtime earlier in the cases they resist all together and you know they’re exhausted. Here is a link to a free guide with tips on naps that may help: https://www.babysleepsite.com/free-baby-nap-guide/
        We also have an ebook all about Mastering Naps & Schedules that may help! Our sample schedules are amazing, but they may need to be tweaked slightly for your specific baby/life so this book is really helpful for that: https://www.babysleepsite.com/mastering-naps/
        I hope this helps!

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