Common sleep problems

Most parents of young children encounter sleep problems of some kind. Here we review the most common challenges, why they occur and what the research says.

Difficulty falling asleep

Many children have difficulty winding down and falling asleep.¹ The ability to fall asleep involves transitioning from an alert, active state to a calm, sleepy state. This transition requires self-regulation – a skill that matures gradually.¹

A particularly demanding period often occurs around 6–8 weeks of age, when crying reaches a natural peak. This is sometimes called the "Period of PURPLE Crying" and is a universal pattern observed in every culture studied.² The crying is often concentrated in the late afternoon and evening, and the baby may be difficult to soothe. At the same time, sleep architecture matures: the proportion of deeper sleep increases, which requires more active winding down, and the baby's growing awareness of the surroundings can make falling asleep harder.³ Together, this makes the period one of the most sleep-disrupting for both the child and the parents. About 10–20 % of all infants cry so much they meet the criteria for colic, usually defined as more than three hours per day, at least three days per week. Colic typically subsides around 3–4 months of age.⁴

Colic is not a disease but the upper end of a normal spectrum. Despite the name deriving from the Greek word for the large intestine, colic has no connection to gastrointestinal problems in the vast majority of cases.⁵ Infants with and without colic show the same type of crying and the same daily pattern, just in different amounts.⁵ The variation between infants is large: at the peak, a quarter of all infants cry more than 3.5 hours per day, while another quarter cry less than 1.7 hours.⁵ What drives the most stress in parents is not the total amount of crying but the episodes when the baby is inconsolable, roughly 5–10 % of all crying episodes, which can last 40 minutes or more.⁵

Beyond age and maturity, temperament plays an important role. Children who are more easily stimulated, intense or who have difficulty managing transitions tend to need more support to fall asleep.⁶ External factors such as too much stimulation near bedtime, irregular routines, screen light and strong sleep associations can also make falling asleep harder.⁷

A predictable evening routine can facilitate falling asleep. The routine need not be long but should be consistent and calm.⁷ ⁸ ⁹ Dimming lights and reducing stimulation near bedtime can also help. If the child depends on a specific sleep association (e.g. being rocked or breastfed to sleep), changing the falling-asleep routine can help the child develop other ways of falling asleep.¹

Frequent wakings

It is biologically normal for children to wake several times per night, but it can be draining for the whole family. Infants have shorter sleep cycles (about 45–50 minutes) compared with adults (about 90 minutes). At each cycle transition there is a brief awakening, and if the child cannot fall back asleep independently they may signal for help.¹⁰

Hunger is a common cause of night wakings during the first months. As the child grows, the physiological need for night feeds decreases, but the habit may persist.¹¹ Periods of new motor development, illness, teething and changes in daily life can temporarily increase the number of wakings.¹² ¹³ The popular concept of "developmental leaps" (Wonder Weeks), however, lacks scientific support. The proposed regression periods have not been confirmed in replication studies.¹⁴

Most infants wake 2–6 times per night during the first 6 months. Wakings decrease gradually, but temporary periods of worsening are common. By 12 months of age many children sleep for longer continuous stretches, but about 20–30 % of one-year-olds still wake regularly at night.¹⁰ Children waking at night is not necessarily a problem that needs to be fixed. It depends on how the family is affected and what works in the individual situation.

Short naps

Short naps – often under 45 minutes – are frustrating for many parents. But they are common and often completely normal, particularly in younger infants. Infant sleep cycles are approximately 45–50 minutes long, and a short nap often means the child wakes after a single sleep cycle without managing to link into another.¹⁵ The ability to link sleep cycles during the day matures later than at night. Many children do not start taking longer naps until around 5–6 months of age.¹⁶

Overtiredness can lead to shorter and poorer sleep. Sleep is regulated by two systems: sleep pressure (which increases the longer the child is awake) and the circadian rhythm (the biological clock).¹⁷ When a child is kept awake longer than these systems expect, cortisol levels – the body's stress hormone – rise as a compensatory wakefulness response.¹⁸ Cortisol interferes with falling asleep and makes sleep lighter, which can lead to the child having difficulty falling asleep despite being tired and waking earlier than expected.¹⁹ This can create a negative spiral where short sleep leads to more overtiredness and an even shorter next nap.

Short naps are not always a problem. If the child seems well-rested, is in a good mood and is developing normally, they may be sufficient for that particular child.¹⁶

Early mornings

Children often wake early – before 6 a.m. – and this is a common concern. Children's circadian rhythm is naturally shifted towards early mornings. The biological clock is driven by light exposure and tends to make young children early risers.²⁰ Sleep pressure is at its lowest at the end of the night, making the last sleep cycle the lightest. Even minor disturbances like light, noise and hunger can cause the child to wake and not fall back asleep.¹⁰

Too early a bedtime can sometimes lead to early wakings if the child has already met their total sleep need. On the other hand, too late a bedtime can cause overtiredness and even earlier mornings.¹⁹ Blackout curtains are one of the most effective measures, since morning light is a strong signal to the biological clock.²⁰ A waking time between 06:00 and 07:00 is typical for most young children.¹⁰