If your baby looks exhausted but somehow seems to fight sleep even harder, overtiredness may be part of the picture.

It sounds contradictory. After all, a tired baby should sleep better, right?

Not always.

In fact, when a baby becomes too tired, sleep can actually become harder.

There is a point where tired becomes too tired. When a baby misses their sleep window, their body can shift into a more alert state. Stress hormones such as cortisol rise, making it harder to settle, harder to stay asleep and often leading to lighter, more fragmented sleep.

This is why an overtired baby can look completely exhausted and, at the same time, strangely awake.

And here is the tricky part: overtiredness does not always look like tiredness.

We tend to think of a tired baby as one who is yawning, rubbing their eyes or becoming fussy. But some of the earliest signs that a baby is ready for sleep can be much quieter.

They may become less interested in playing, turn their face away, stop engaging as much or develop that slightly glazed, distant look. Their movements may slow down, and they may simply seem less interested in what is happening around them.

If that natural moment for sleep passes, the signs can become much more obvious. You might notice:

• sudden fussiness or crying before sleep
• difficulty settling, even though your baby is clearly tired
• a surprising burst of energy or “second wind”
• short naps
• waking shortly after bedtime
• more frequent night wakings
• early morning wakings

None of these, on their own, mean that your baby is overtired. But if a few of them are starting to sound familiar, sleep timing may be worth a closer look.

Your baby was tired. You were sure they were ready for sleep. And then, suddenly, they seem wide awake again.

Maybe they are playing, wriggling around or looking at you as if sleep was never on the agenda.

It can be tempting to think, maybe they weren't tired after all.

But sometimes, the opposite is true.

When a baby stays awake beyond their sleep window, their body can become more alert. That sudden burst of energy does not necessarily mean they no longer need sleep. It may mean that falling asleep has just become harder.

Overtiredness is often about timing.

There is a natural sweet spot when your baby has built up enough sleep pressure to fall asleep and their body clock is also ready for sleep. This is their sleep window.

If that window passes, settling can become much harder.

And when this happens repeatedly, tiredness can begin to build. A short nap can make the next sleep more difficult. A difficult day can lead to a harder bedtime. A fragmented night can mean starting the next day already carrying some of that tiredness.

Before long, it can feel as though sleep has suddenly unravelled.

The good news is that preventing overtiredness is not about finding one perfect minute every day. Babies are not clocks.