7 minute readWhat is active sleep?
For babies, active sleep is similar to what we refer to as REM (rapid eye movement) sleep in adults — characterized by continuous movement of the eyes under the lids, irregular breathing, increased brain activity, and often a slightly faster-than-normal heart rate.
But while adult REM sleep and baby active sleep share many similarities, there’s one quite crucial difference: when adults enter REM sleep, their bodies usually stay quite still (save for the odd twitch here and there), while babies in active sleep are often very fidgety. It’s common for them to twitch, wriggle, jerk, and even pull faces.
Babies in active sleep can also be pretty vocal, so it’s not unusual for them to make grunting, whimpering, or crying sounds. It’s this combination of sound and movement that can often mislead a parent into believing their little one is awake rather than in the throes of active sleep.
But while it can be concerning at first to see your baby appearing restless, twitchy, or whimpering in their sleep, it’s a totally normal sleep stage for a newborn — and in fact, it’s an important part of their sleep cycle, since it’s thought to play a key role in their brain’s early development.
What are the signs of active sleep in babies?
When your baby is in active sleep, they’re not in a deep, restful state but a lighter stage of sleep where they’re typically more responsive to external stimuli. So while they’re still very much sleeping, they’ll often make little movements or sounds — from throwing their arms in the air to making ‘cooing’ or ‘gurgling’ noises.
Your baby is probably in active sleep if they’re doing any or all of the following:
Moving their body. Active sleep in babies is often accompanied by lots of movement; they may twitch, wriggle, squirm, or move their arms and legs.
Twitching their eyes. Like REM sleep in adults, babies’ eyes are often moving even though they’re asleep — so you may notice their eyelids fluttering.
Pulling faces. When in active sleep your baby might make facial expressions such as smiling, frowning, or grimacing.
Making sounds. Babies often make small noises during active sleep — grunting, whimpering, and gurgling are common.
Breathing erratically. While it’s usually nothing to worry about, babies’ breathing is often faster and more irregular during active sleep.
How long does active sleep last in babies?
For newborns, active sleep is the first stage of sleep they experience, unlike in adults where REM sleep begins around 90 minutes after first dropping off.
Between the ages of 0 and 3 months, babies typically spend around 50% of the time they’re sleeping in active sleep, with the rest made up of “quiet sleep” — which we’ll come to very shortly. Since a newborn sleep cycle usually lasts around 50-60 minutes, active sleep will last for roughly 25-30 minutes at a time — though of course, this can vary based on your baby’s age and development.
As your baby gets older, they’ll usually spend less and less time in active sleep. By the time they reach 12 months, for example, active or REM sleep will make up around 30% of their total shuteye, with their sleep cycle more closely resembling an “adult” cycle (which includes around 20-25% of REM sleep) by about the age of 5.
How does active sleep differ from “quiet sleep”?
Newborn sleep cycles tend to include two different types of sleep — active and quiet sleep — with each cycle split roughly 50/50 between one and the other. The cycle starts with active sleep, where your baby’s little eyes dart about under their eyelids and their brains are still whirring away, before transitioning to quiet sleep.
By the time they reach the quiet sleep stage (which is sometimes referred to as non-REM or NREM sleep), your baby is in a deeper, more restful state. They’ll often fully relax (no more wriggling limbs) and their breathing will become slow, deep, and more regular. Their brain is far less active during this stage, which is why they’re less likely to move around, pull faces, or make noises — hence the term quiet sleep.
This pattern of active-to-quiet sleep plays a key role in your baby’s early growth and development, with active sleep thought to be pivotal in developing their brain and quiet sleep more focused on physical development.
How do I tell if my baby is awake or in active sleep?
Because babies tend to be quite restless and often a little “chatty” during active sleep, it’s not always easy to tell if they’re sleeping or awake. Small or sudden movements during active sleep can be mistaken for signs of wakefulness, while their occasional whimpers may make it seem like they’re trying to get your attention.
However, these kinds of behaviors are normal during this lighter sleep stage and don’t necessarily indicate that they’re awake — or about to wake. Fortunately, there are a few key signs that can help you tell whether your baby is in active sleep and can be left to rest or they’re awake and trying to tell you they need something!
Active Sleep | Awake |
Eyes: Closed, but often with fluttering eyelids indicating rapid eye movement (REM). | Eyes: Fully open and focused, looking around or engaging with surroundings. |
Movements: Often random, brief twitches or jerks of arms, legs, or face. | Movements: More purposeful and sustained, such as stretching or reaching out. |
Breathing: Irregular, with varying speeds or short pauses. | Breathing: Steady and regular, reflecting more consistent body rhythms. |
Sounds: Occasional grunts, whimpers, or short cries that don’t persist. | Sounds: Continuous crying or fussing until comforted, showing clear signs of distress or need. |
Why is my baby crying during active sleep?
It’s quite common for babies to make whimpering sounds or even cry briefly during active sleep, but this isn’t usually a sign of distress or discomfort. Your baby’s nervous systems are still maturing at this early stage of their development, and this can cause them to make involuntary sounds during sleep, including occasional crying noises.
As long as your baby’s cries are occasional and short-lived — and they settle down quickly and continue sleeping in between each whimper — there’s normally no need for concern. If the crying persists, escalates, or if they seem genuinely distressed, however, you may want to check on them as they’re likely in need of attention.
Should I wake my baby if they’re restless during active sleep?
While it can be tempting to try to wake your baby or pick them up when they appear restless during active sleep — especially if they’re very wriggly or making lots of whimpering sounds — it’s best to let them sleep unless they appear distressed.
Restlessness during the first 25-30 minutes or so of sleep is perfectly normal for a newborn, and just because they’re wriggling, twitching, whimpering, or grumbling it doesn’t necessarily mean they’re agitated or uncomfortable. They’ll soon transition into a more peaceful, quiet sleep.
Of course, if you have any concerns about your baby’s sleep patterns — for example, if they show unusual sleep behaviors such as prolonged or very irregular breathing patterns, or they seem to be struggling to sleep at all — it’s always best to consult a healthcare professional.
The question of whether your baby is awake or in active (REM) sleep is just one of many you’ll likely ask during the early stages of parenthood.
But while it can be difficult to tell the difference between a newborn who’s just sleeping restlessly and one who’s awake and in need of comfort, picking up on the telltale signs of active sleep can help you determine when the time is right to leave your baby to rest — where they’ll soon drift into a quiet, peaceful sleep.
Looking for a full breakdown of your baby’s sleep cycles at each stage of their development? Check out our Baby Sleep Cycle Guide by Age.