Under 2's

The science of sleep: Part I

  • The science of sleep: Part I

Sweet dreams

Sleep can become a stressful business when infants are involved. In the first of two articles, Sarah Ockwell-Smith looks at the science behind our under-twos’ shuteye, and suggests ways to support struggling parents…

Did you know around 60 per cent of the parents at your setting think that their child has a sleep problem? By far the most common concern of parents is that of night waking and not ‘sleeping through the night’. Ironically, given this worry, nobody actually sleeps through the night – child or adult. Sleep is not that simple. We don’t just go to sleep at night and wake in the morning; we move through a series of different sleep cycles and often wake in between. The main two phases of sleep are known as ‘rapid eye movement’ (REM), or ‘active sleep’, and ‘non- rapid eye movement’ (NREM) or ‘quiet sleep’.

At the start of a sleep cycle we enter NREM, moving from a drowsy state through to a light sleep to a much deeper level where arousal based on environmental triggers is minimal. At the end of this phase we move into REM, which is a bizarre blend of deep sleep and a high level of brain activity. REM sleep plays host to vivid dreams and nightmares, whilst NREM is the host to night terrors and bed-wetting. At night we move through different cycles of REM and NREM, and often wake at the end of a sleep cycle, although sometimes we may be so drowsy we don’t remember it. An average adult sleep cycle lasts for around 90 minutes, whereas for an under-three-year-old it is around 45. This means that, on an average night, an adult has around five sleep cycles, whereas an under-three will have an average of 10. Or in other words, children have 10 chances of waking between sleep cycles at night if their needs aren’t met or something startles them. When you think of it this way, it’s a miracle that the average nursery-aged child only wakes once every night!

Babies & toddlers

A baby will spend between 40 and 50 per cent of their sleep in REM. For a one-year-old this figure will be around 35 per cent, and for a two-year-old, around 30 per cent. Contrast this to an adult who spends on average only 20 per cent of their sleep in REM. We know that SIDS (Sudden Infant Death) occurs in NREM, where arousal is inhibited, therefore having more REM sleep is beneficial to them. To their parents, however, it means they wake regularly, often at the end of every 40- minute sleep cycle – whether a daytime nap, or during the night, which many consider a ‘problem’. Biologically speaking, however, it’s anything but a problem: it’s life saving! We want babies to spend more time in REM sleep in order to protect them; however, we try desperately to get them to sleep for longer by using methods, such as swaddling, for instance, known to increase NREM sleep – the sleep where SIDS occurs. There is almost always a price to pay for forcing infants to take more (deeper) sleep than they are biologically programmed for.

The difference in REM sleep also impacts toddlers. Remembering this is where nightmares come into play, combine this with the vivid imaginations of toddlers, and we can understand why so many wake after bad dreams, are scared of sleeping alone,
without a light or with the door closed.

Western, Caucasian countries, are quite unique in keeping babies and children in different bedrooms to those of their parents. Worldwide, around 70 per cent of underthrees sleep in the same room as their parents, if not the same bed. This is particularly common in Asia, where interestingly they report far fewer sleep problems than parents in the West. In Hong Kong, SIDS is so rare that they don’t even have a name for it, and the same is true in Japan for ‘colic’ – surely no coincidence? Many scientists today believe that if done following simple safety guidelines, cosleeping can not only improve sleep for all but actually reduce SIDS and improves the emotional and physical health and cognitive functioning of the child in later life.

Supporting parents

Many parents struggle with their children’s sleep, and it can be helpful to reassure them and/or offer suggestions if their problems are ongoing.

1 Reset expectations. The tables indicating how long a child should sleep for by age are based on opinion only, not scientific evidence. All children are different – some need more sleep, some need less. Babies and toddlers by nature are ‘poor’ sleepers; this is totally normal and certainly not an
indication of any parenting failure!

2 Encourage parents to make changes in their life to cope better. Can they go to bed earlier, get some help around the house or catch up on sleep at weekends?

3 Parents may consider ‘rooming in’ or bedsharing for a while. See ow.ly/tWeHv for important safety guidelines.

4 Children shouldn’t be put to bed too early. Recent research has shown that toddlers in the UK are being tucked in before the worldwide average bedtime for 0–3-year-olds of around 8:30pm (this is the time scientists found works best for most toddlers). A baby or toddler at daycare also needs time for the cortisol levels (the hormone that keeps us awake and active) to fall after returning home, which, research tells us, takes around two hours. In other words, children need to be at home from nursery, winding down, for at least two hours before bedtime.

5 Remove as much light as possible from the bedroom. Electric lighting, particularly modern energy-saving light bulbs and blue/white/yellow coloured children’s night lights, inhibit melatonin – the hormone of sleep. The best option is no light source, but if the child is scared, use a red bulb, which doesn’t inhibit melatonin

6 Children can be conditioned to take comfort from a certain scent (lavender or camomile are great), sound (an ‘alpha music’ CD works well) or object (such as a teddy bear) in the hopes that this will comfort them enough when they wake that they will not need adult input. This takes time, though – at least a month – to produce any effects.

7 ‘Wait it out’. Remind parents that this won’t last forever, that their child will start to sleep more as they get older – and one day they will have a teenager who refuses to get out of bed before lunchtime! My favourite parenting phrase is “this too will pass” – and so it will!

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