You've finally got your baby to sleep — and now they're grunting, twitching, and pulling faces. Before you panic, understand that this is completely normal newborn behaviour called active sleep.
What Active Sleep Is
Newborns cycle between active sleep (similar to adult REM sleep) and quiet sleep. In active sleep, the brain is highly active — almost as active as wakefulness. Eyes may move under eyelids, limbs may jerk, facial muscles move, and the baby may make sounds.
| Active Sleep | Quiet Sleep |
|---|---|
| Eyes flicker under lids | Eyes still |
| Facial expressions: smiles, grimaces | Face relaxed |
| Grunting, squeaking, small cries | Silent |
| Limb twitches and jerks | Still |
| Easily disturbed | Harder to wake |
Why Newborns Have So Much Active Sleep
Newborns spend about 50% of sleep time in active sleep, compared to about 20% for adults. This is because active sleep is the primary driver of brain development in early life. The brain generates its own electrical activity during this phase, wiring up neural circuits — a process called endogenous stimulation.
The Grunting Specifically
The grunting sounds most parents hear are produced by the vocal cords vibrating with breathing during active sleep. They are not a sign of respiratory distress. Grunting that occurs primarily during sleep (not during wakefulness) is almost always benign.
Important distinction
Grunting that happens with every breath while the baby is AWAKE, along with flared nostrils, retractions (skin pulling in between ribs), or pale/blue colour, IS a sign of respiratory distress — seek medical help.
Why You Should Wait Before Responding
Because newborns make sounds and movements during active sleep, many new parents rush in at every noise and accidentally wake their baby. If your baby is making sounds but their eyes are closed, wait 60–90 seconds before intervening — they may settle back into quiet sleep on their own.
The Newborn Sleep Cycle Length
Newborn sleep cycles last about 45–50 minutes. They cycle between active and quiet sleep multiple times per sleep period. The transition between cycles — where the baby partially arouses — is when most night wakings happen and when active sleep sounds are loudest.