Understanding Newborn Twitching: What's Normal?

Twitching is a common occurrence in newborns and infants, and it is often a normal part of their development. This phenomenon, known as sleep myoclonus, is characterised by sudden muscle contractions or relaxations that result in twitching during sleep. While it can be concerning for parents, it is usually harmless and indicative of a developing nervous system and brain. Researchers have linked these twitches to sensorimotor development, suggesting that they may play a role in teaching newborns about their limbs and how to coordinate their movements. However, in rare cases, twitching can be a sign of a more serious condition, such as infantile spasms or seizures, and it is important to seek medical advice if twitching occurs when the baby is awake.

Twitching during sleep is normal

Twitching during sleep is a common phenomenon in newborns. While it may be alarming for new parents, it is often a harmless display of your baby's developing nervous system at work. This phenomenon is called benign sleep myoclonus, a type of twitch caused by sudden muscle contractions or muscle relaxation. It is no more dangerous than another form of myoclonus: hiccups!

Babies have an immature nervous system, and their movements are even more uncoordinated during sleep than when they're awake. These twitches are believed to be linked to sensorimotor development, with the sleeping body activating circuits throughout the developing brain and teaching newborns about their limbs and what they can do with them. Researchers have observed that when babies start reaching for things, there is an increase in twitching in the wrists and fingers.

Studies have shown that these movements are harmless. However, if you are concerned about your baby's twitching, it is always best to consult a healthcare professional. They will be able to assess the situation and provide guidance or reassurance.

It is important to note that twitching during sleep is different from infantile spasms, a rare type of childhood epilepsy that can impact a baby's development. Infantile spasms typically occur when a baby is between 3 to 12 months old and are characterised by clusters of tiny seizures that last a second or two. If you notice any signs of infantile spasms, it is crucial to seek medical advice as early diagnosis and treatment are critical to your baby's development.

When to seek help for newborn twitching

Twitching during sleep is a common occurrence in newborns and is often harmless. However, there are certain instances where you should seek medical help.

Firstly, if your baby is experiencing twitching or stiffening when they are awake, this may be a sign of a seizure issue, and you should contact a healthcare professional.

Secondly, if you notice abnormal eye movements along with body movements, this is a key indicator of a true seizure, and you should call an ambulance or go to the emergency room immediately.

Thirdly, if your baby is having trouble breathing, or turns blue, purple, or grey, seek emergency medical attention.

Finally, if your baby is twitching and also experiencing poor feeding, dehydration, or poor colour or tone (yellowish, bluish, or greyish), take them to the emergency room or their pediatrician as soon as possible.

While newborn twitching is usually benign, it is always better to ask a healthcare professional if you are concerned.

The difference between infantile spasms and normal movements

It is very common for newborns and infants to startle. They fling their arms and legs wide, then bring them together. In most cases, this is a normal reflex known as the startle, or Moro, reflex. However, in rare cases, these movements may be a sign of a serious condition called infantile spasms.

Infantile spasms are a rare type of epilepsy that affects approximately 1 in 2,000 infants and children in the US each year. The spasms are tiny seizures that can have a big impact on a baby's development. They can cause serious, permanent changes to a child's developing brain without early diagnosis and treatment.

Infantile spasms can be challenging to distinguish from normal movements. While classic spasms include jerking of the neck, trunk, and extremities, some signs are very subtle, such as eye rolls or head drops.

Frequency: Loud noises, bright lights, or sudden movements can trigger a baby to startle. But unlike that single startle reflex, infantile spasms typically happen back-to-back or in clusters. Each spasm may last only a second or two, but a cluster can last several minutes.

Timing of Spasms: Infantile spasms often occur when the baby is waking up from sleep, and they will often cry after the spasm. On the other hand, normal startle reflexes can occur at any time, regardless of the baby's sleep state.

Baby's Age: The startle reflex is most noticeable in newborns and slowly disappears by 4 to 6 months of age at the latest. Infantile spasms, on the other hand, often occur between the ages of 3 to 12 months, when the startle reflex has already started to fade.

Baby's Development: Another telltale sign of infantile spasms is a decline in development. You may notice that your baby is no longer doing things they used to be able to do, or you may see changes in how your child interacts with you, such as less eye contact or smiling.

If you suspect your baby is experiencing infantile spasms, it is important to seek medical advice as early diagnosis and treatment are critical to stopping the seizures and reducing their impact on your baby's development.

Benign sleep myoclonus

Benign neonatal sleep myoclonus (BNSM) is a self-limiting disorder characterised by myoclonic jerks during non-rapid eye movement (NREM) sleep. BNSM is often mistaken for seizures during the newborn period, prompting hospital admissions and extensive diagnostic testing. However, it is important to differentiate BNSM from other serious causes of neonatal seizures.

BNSM is characterised by myoclonic "lightning-like" jerks of the extremities that exclusively occur during sleep and are not correlated with epilepsy. These jerks can be unilateral, isolated, or repetitive and can transition from one limb to another. The defining feature is that the movements stop immediately upon waking. The underlying cause of BNSM is unknown, but it may be related to structures or pathways that subserve sleep. There is also a suspected genetic component, with reports of occurrence in multiple family members.

The diagnosis of BNSM can be challenging and requires a thorough understanding of the phenomenon to avoid unnecessary testing. An electroencephalogram (EEG) may be required to distinguish BNSM from neonatal convulsions, as there are no associated EEG abnormalities in BNSM. Other investigations, such as brain imaging, are typically not helpful.

While BNSM is a benign condition, it can cause concern for parents and healthcare professionals. It is important to recognise and differentiate BNSM from more serious neurological conditions to prevent unnecessary interventions and parental anxiety.

The link between twitching and sensorimotor development

Twitching is a defining feature of active REM sleep, which is most prominent in early infancy when critical sensorimotor networks are being established. While twitching was previously thought to be a meaningless spasm or a movement related to dreams, researchers now believe that these twitches contribute to sensorimotor development.

Twitching movements during REM sleep activate circuits in the developing brain, teaching babies about their limbs and what they can do with them. This is known as processing sensory input and mapping the sensorimotor system. Studies with mammals and birds show that there is plenty of REM sleep during early development, suggesting that twitching helps to synchronize developing structures and strengthen neural connections.

Twitching is also thought to be a form of motor exploration, where animals probe the structural features of their limbs and build motor synergies, thus laying the foundation for goal-directed wake movements. In other words, twitching helps babies transform their rudimentary movements into coordinated movements.

The discrete nature of twitching is important for establishing and refining connections in the sensorimotor system. Twitching movements are spontaneous and not evoked by an external stimulus, yet they are not random. They occur exclusively during periods of active sleep and exhibit a complex structure.

The sensory feedback arising from twitching limbs is processed differently than the feedback from wake movements. This difference in sensorimotor processing provides strong evidence that twitching is uniquely suited to drive certain aspects of sensorimotor development.

In summary, twitching during REM sleep is now understood to be an important contributor to a baby's motor skills development and sensorimotor development. By activating circuits in the developing brain, twitching helps babies learn about their limbs and refine their movements.

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