Sleep stages

Babies have two sleep states: deep or quiet sleep and active or light sleep (also called rapid eye movement or REM). Additionally, they also experience other “behavioural states” raging from drowsiness, being quietly or actively awake, being fussy to crying.

It is not always easy to know in which behavioural state a baby is in. However, understanding the different behavioural states can help parents to know when their baby will be ready for interaction and when it is time to support their baby to get some rest.

1. Deep/quiet sleep

In this state a baby moves very rarely apart from occasional startles or mouthing. The breathing is slower and more regular than in the other stages. After 32 weeks gestational age this sleep state becomes more noticeable.

2. Light/active sleep

In this sleep state the eyes of the baby are closed, but slowly rolling eye movements, also called rapid eye movements (REM) can be observed. Breathing tends to be faster and more irregular and a baby may briefly open the eyes or make sucking movements. For adults, this stage is associated with dreaming. In this state, brain connections are also modified which is particularly important for the developing brains of babies.

3. Drowsy

In this stage a baby’s eyes may open and close, but have a shiny appearance. It is also called half-awake, as the baby may be in a stage of waking up or falling back to sleep again. In this stage the care givers can either support the baby to fall back to sleep again, e.g., by putting the hands gently on the head and feet of the baby, or start to gently wake up the baby for a care procedure, e.g., a nappy change.

4. Quietly awake

When babies grow and mature, they can achieve a stage where they have wide-open eyes with a bright look and a relaxed facial expression. Babies in this state can focus on a voice, face or object. It is a good time to have care procedures such as feeds, or skin-to-skin care.

5. Actively awake

At this state a baby’s eyes can be open or closed. The child may seem restless or troubled, making movements often accompanied by grimacing or sounds. In this stage, the baby needs help to settle again and to cope with the environment.

6. Crying

Crying is the most stressful state for the baby, the parents, and the health care team. During crying the baby shows generalised movement with agitated sounds, grimacing, and crying expression of the face. Breathing may be irregular and skin colour can change.

Different factors can promote the sleep of a baby in the neonatal intensive care unit.

For example, the healthcare team will figure out the optimal timing for care or medical procedures in relation to state of arousal of the infant. If possible, care givers avoid disturbing the baby for procedures when the infant is in a sleep state.

They also care about an appropriate environment, by adapting noise and light to the stage of sleep or alertness.

Comfortable positioning can help the baby to settle and get more sleep.

The care team may move towards feeding according to the baby’s need as soon as baby shows sleep cycles maturing and readiness to feed. 

The involvement of parents can also improve the sleep of a preterm baby. Parents interact with their baby in a different way and can take more time to manage transitions and to settle their baby to sleep. Additionally, the skin-to-skin care and the parents’ voice can promote sleep. The healthcare team can show parents how they can support their baby in the optimal way to achieve a restful sleep.