Is Overtiredness a Myth? An Exploration into the Impact of Daytime Naps on Nighttime Sleep

If you’ve done any reading on sleep, you’ve probably come across the word “overtiredness.” It’s a term that often appears in sleep accounts and articles, and not without controversy—some sleep experts blame almost every sleep issue on this phenomenon, while others try to deny its existence altogether.

So what is it, and how does it actually impact our little ones’ sleep?

Understanding Overtiredness

Overtiredness occurs when a little one is awake longer than is ideal based on their age, individual sleep needs, and developmental stage. To understand this further, it is important to grasp the role of cortisol. Often known as “the human wake hormone,” cortisol is produced naturally by our brains to help us wake up in the morning. Cortisol is essential for human life and well-being; without it, we wouldn’t be able to wake up!

However, when a little one is awake for too long, their body produces extra cortisol to give them a “second wind.” The excess wake hormone in their system can then lead to bedtime battles, multiple night wakes, short naps, and early starts. And thus, the cycle of overtiredness is born.

Ensuring your little one has adequate daytime sleep is key to achieving good nighttime sleep. It is a commonly believed myth that keeping a baby awake longer during the day will increase the chances of them sleeping better at night—in fact, the opposite is true! A baby who is not sufficiently rested is likely to resist the sleep they desperately need, while a well-rested little one has the foundation to achieve consolidated stretches of restorative nighttime sleep.

How to Prevent and Reverse Overtiredness

Use Age-Appropriate Wake Windows and Sleep Cues

Using both age-appropriate wake windows and observing your little one’s sleep cues will keep you on track. Wake windows specify the length of time that a little one should be awake from the end of one sleep to the beginning of another. Monitoring these windows will prevent you from missing sleep cues and inadvertently allowing your little one to stay awake too long. It is important to remember, however, that wake windows are based on averages; while they provide a good guide for your baby at any given age, there is always a range within which your baby will fall. Being familiar with their sleep cues will therefore help you tailor your baby’s day to their unique needs. Your baby will indicate that they are ready for bed by zoning out, staring into the distance, exhibiting a pinkish tinge around their eyebrows or eyelids, and showing a reluctance to interact or focus. If your little one is already fussing, crying inconsolably, clenching their fists, or arching their back, you may have missed their optimal nap time.

Don’t Fear a Late Afternoon Power Nap

Many parents fear that a late power nap might ruin bedtime. However, skipping a late afternoon nap in favor of a longer wake window before bed is likely to make bedtime more difficult. Introducing a short nap to maintain an optimal wake window before bed can be a game changer.

Embrace Early Bedtimes

Sometimes, naps don’t go as planned. A change in environment—such as starting a new childcare setting—may disrupt your little one’s normal sleep patterns. Or perhaps a nap ended earlier than ideal, leaving insufficient time for a power nap before bedtime and creating a gap that is too long. To prevent overtiredness in these instances, consider putting your little one to bed up to an hour earlier than usual. And don’t worry—if your little one needs it, an early bedtime doesn’t mean they will wake up an hour earlier than normal. Taking steps to reduce cortisol levels will likely result in a later start—and a less disrupted night—than you might have otherwise experienced.

Work on Longer Naps

It is not uncommon for little ones to struggle with daytime sleep. During the day, our biology doesn’t support sleep in the same way, as melatonin levels are significantly lower than at night. Additionally, a baby who has not yet learned to connect their sleep cycles will struggle to nap for longer than a single cycle, which in babies is around 40–45 minutes. Short naps, apart from being challenging for the parent who has battled to get their little one to sleep, are not sufficiently restorative. A baby who only sleeps for 40 minutes at a time is likely to wake up upset because they are still tired, potentially leading to irritability and difficulties with feeding or play. The long-term solution is to teach your child to self-settle at the beginning of a nap so that they can return to sleep independently when they wake briefly between sleep cycles. In the meantime, try to resettle your little one if they wake after a single sleep cycle, and if that fails, shorten the wake window until their next nap to prevent overtiredness.

Use Contact Naps, Motion, or Driving to Ensure Daytime Sleep

While independent sleep is important for long-term improvement, if your little one struggles to fall asleep on their own, prioritize sleep over the location where your little one sleeps. For example, some babies resist the final nap of the day due to low melatonin levels and a buildup of tiredness over the course of 12 waking hours. Even if your little one normally naps well in the cot, ensure that they get the sleep they need in the safest and most convenient way possible. This might mean cuddling them in a baby carrier, taking them for a walk in a pram, or even allowing a short nap in the car for quick shut-eye until bedtime. Ensuring that your little one gets their naps is far more important than the location where those naps occur—especially if you think they might be struggling with overtiredness.