TL;DR
When babies struggle to fall or stay asleep, it often comes down to timing. An overtired baby produces stress hormones that fight sleep, while an undertired baby simply is not ready to rest. Learning to recognise the difference - and adjusting wake windows and cues - can transform sleep quality. Gentle, repetitive soothing like Lullabear™’s rhythmic patting helps reset your baby’s body when timing slips off track.
5-Point Summary
- Overtired babies release cortisol, making it harder to sleep.
- Undertired babies lack enough sleep pressure to settle.
- Watching cues and wake windows is key to balance.
- Consistent routines teach the body when to rest.
- Rhythmic, gentle comfort helps realign sleep readiness.
Why Timing Is Everything
Most baby sleep struggles are not about your baby being “bad at sleeping.” They are about timing. Babies’ bodies work on natural rhythms, and when those rhythms are off, even the best bedtime routine will feel like a battle.
The Sleep Foundation explains that both too much and too little wake time can cause restlessness. The trick is knowing which one you are dealing with — overtired or undertired.
Understanding Overtiredness
When babies stay awake too long, their stress hormones (especially cortisol and adrenaline) rise. These hormones keep them alert when their bodies are begging for rest. This creates what most parents describe as “wired but tired.”
Signs of an Overtired Baby:
- Rubbing eyes or ears
- Sudden bursts of energy followed by crying
- Clinginess or resistance at bedtime
- Short naps and frequent night wakings
- Difficulty settling even when clearly exhausted
Overtiredness can happen fast - especially in younger babies whose wake windows are short. Once cortisol spikes, the body needs extra time to calm down.
Understanding Undertiredness
An undertired baby, on the other hand, simply is not sleepy enough. They may look calm but resist lying down because their body has not built enough “sleep pressure.” This often happens when naps run too long or are too close to bedtime.
Signs of an Undertired Baby:
- Playing or chatting in the crib instead of sleeping
- Laughing or kicking during bedtime routine
- Taking a long time to fall asleep but waking happy
- Short naps followed by good energy
The American Academy of Pediatrics (AAP) notes that both over- and undertiredness can disrupt circadian rhythm, but overtiredness is usually harder to fix because stress hormones keep the body awake even when tired.
Finding the Sweet Spot: Wake Windows by Age
| Age | Typical Wake Window |
|---|---|
| 0–2 months | 45–60 minutes |
| 2–4 months | 60–90 minutes |
| 4–6 months | 1.5–2 hours |
| 6–9 months | 2–3 hours |
| 9–12 months | 2.5–3.5 hours |
| 12–18 months | 3–5 hours |
These are guidelines, not strict rules. Every baby’s rhythm is slightly different. The key is watching your baby’s tired signs - yawns, glazed eyes, slower movement — and putting them down before overtiredness sets in.
How to Fix Overtiredness
-
Reset with Early Bedtime:
If your baby has had a rough day of short naps or long wake times, move bedtime up by 30–60 minutes. -
Shorten Wake Windows for a Few Days:
Help their body recover by keeping them on the lower end of the recommended wake time range. -
Use Calm, Predictable Cues:
Dim lights, quiet voices, and gentle touch tell the body to slow down. The rhythmic patting motion of Lullabear™ helps calm your baby’s nervous system and reduce cortisol naturally. -
Avoid Overstimulation Before Bed:
Turn off screens, skip high-energy play, and create a simple wind-down window before sleep.
How to Fix Undertiredness
-
Slightly Extend Wake Time:
Add 10–15 minutes of awake play before the next nap or bedtime. -
Encourage Active Play:
Use tummy time, songs, or exploration to help build more sleep pressure. -
Cap Naps Strategically:
If your baby takes long late-day naps, gently wake them to protect bedtime. -
Stay Consistent with Routines:
The more predictable your cues — bath, feed, patting, lights out — the easier it becomes for their body to know when rest is coming.
The Role of Routine and Soothing
Consistency is what helps babies connect tiredness to rest. Research in Sleep Medicine shows that babies with steady sleep cues fall asleep 37% faster and wake less frequently overnight (ScienceDirect).
Gentle sensory cues like Lullabear™’s soft, rhythmic patting work because they create repetition. Your baby’s body begins to associate that familiar motion with comfort and safety, even when overtired or overstimulated.
Takeaway
Sleep is timing and trust. When your baby is overtired, they need calm and predictability. When they are undertired, they need a little more awake time before rest.
The best tool you have is observation — noticing what your baby’s cues are telling you. Combine that awareness with a steady routine and familiar comfort, like the rhythmic touch of Lullabear™, and you will start finding that sweet spot where sleep finally becomes easier for both of you.