Sleep and children
by Dr Chin Moi Chow
Sleep is regarded an important activity (or rather inactivity) in our life, as most
of us can attest to the fact that we function and behave best after a good night's
sleep. Sleep deprivation, on the other hand, can adversely affect our health and
disposition, with common symptoms such as mood swings, depression, weight loss and
concentration problems - just to name a few.
Parents of young children appreciate the importance of ensuring adequate sleep in
their children. Sleep deprived children are known to behave badly and are unable
to concentrate in school. Moreover, their immunity may become compromised, making
them more susceptible to illnesses. All these can be allayed if children get the
amount of sleep that they need. but how much sleep do they need, you may ask.
To enlighten us on the intriguing subject of sleep is Dr Chin Moi Chow, a senior
lecturer in exercise and sport science at the University of Sydney, Australia. Her
early years of sleep research centred on the mechanism of sleep apnea related to
Sudden Infant Death Syndrome (cot-death). Dr. Chow manages the Delta Sleep Research
Unit located on the Cumberland campus of the University of Sydney. Her current research
examines the role of weight training in treating insomnia. In this article, Dr Chow
also gives parents some useful tips on how they could help their children to overcome
sleep problems as well as steps to determine sleep problems in their children.
Q1) Why is sleep important? What happens in our body when we sleep?
A)The purpose of sleep remains a mystery. What we do know is that
we find it difficult to navigate through the waking hours if we were sleep deprived.
Sleep is a conscious state. You may be surprised that we continue to monitor our
environment even during sleep, particularly following sleep onset when in light
sleep. But unlike wakefulness, our senses are far less alert especially during deep
sleep when we don't arouse as readily. All body systems continue to function during
sleep as in the awake state, but not quite the same way. For example, our muscles
are more relaxed and may be in a paralysed state during dreams; our breathing becomes
slow and regular in deep sleep and may be sporadic and irregular during dreams.
Q2) How much sleep do infants, children and adults need?
A)Babies, children and adults vary widely in the number of hours
they need to sleep in each 24h. In general, normal full-term newborns spend 16-18
of 24h asleep. New babies will sleep whenever they need to as dictated by their
personal makeup. Their sleep-wake cycle is short (around 3-4h) and is therefore
multiple at this age. Sleep consolidates into the night by 4-6 months. The longest
continuous sleep period is extended to 6h. Hence two bouts of long sleep periods
make up the night, with a feed in between. The total sleep needed by infants is
made up of both sleeps during the night and naps during the day. In general, the
3-6 month olds use 3 naps and the 6-12 month olds use 2 naps. Sleep needs decrease
progressively with age. By the first birthday, an infant sleeps between 14-15h/
day. During the toddler years (from 1yr to 2½), the overall number of hours slept
drops only gradually. By the second birthday, the total sleep is reduced by about
one hour. Following the toddler years but before adolescence, the child sleeps well
at night and is wide-awake during the day.
Most young adults sleep around 7.5h during weekday nights and 8.5h on weekend nights.
The length of sleep is often dictated by choice. Thus it is difficult to characterise
a "normal" sleep length.
Q3) Why do we sleep less as we grow older?
A)Research seems to suggest that the total sleep time does not
change with aging. In other words, the need for sleep is the same. In old age, sleep
need is often met through daytime naps. As we grow older, we sleep less mostly because
of sleeping difficulties. (Do note that the ageing process alters the sleep pattern
as defined by brainwave activity). A number of factors may contribute to poor sleep.
Biological aging in many ways alters the sleep quality of the aged affecting the
timing and maintenance of sleep. Aging of the biological clock and organ systems
within the body can impact directly on sleep. For example, physical frailness and
inactivity, mental illness or chronic disease and pain, insufficient light exposure,
poor nutrition, or psychological factors are factors that impair sleep.
Q4) What happens when infants and children do
not get sufficient sleep?
A)Infants and children should normally sleep well unless disturbed
by internal and external factors. Internal factors are those of hunger, pain related
to wind or passing bowel movement, or jerks or twitches of the baby's body as it
relaxes towards deep sleep. Noise and cold may disturb infants and children if they
are not in deep sleep.
What causes an infant or a child to not get sufficient sleep seems an important
question. Disturbed sleep may be due to poor sleep habits (usually a result of parents
setting unrealistic bedtimes that is based on convenience rather than on the child�s
needs). In others it may be related to illnesses or sleep disorders including obstructive
sleep apnea, where there is snoring, pauses in the breathing and increased work
of breathing.
Babies who don't settle into patterns of being soundly and comfortably asleep tend
to be miserable babies, who are tired and fretful. They are irritable, slow and
difficult to feed and not very sociable. Weight gain tends to be slower. For the
toddler, sleepiness may be mild. Overactivity, inattentiveness, whining and difficult
behaviour are often signs of insufficient sleep. In adults and some children, sleep
deficit may cause excessive daytime sleepiness, tension, depression, confusion,
fatigue, poor mental performance and slowed reaction time.
Q5) There are two types of sleep – REM and Non-REM.
What are they and how do they differ from each other? Also, please briefly explain
about the different stages of sleep.
A)Sleep is made up of two sleep states: non-rapid eye movement
(NREM) sleep and rapid-eye movement (REM) sleep. We enter sleep usually through
NREM sleep, which has stages 1,2,3 & 4. We are in light sleep during stages
1&2, and in deep sleep during stages 3&4. Emerging from deep sleep, we move
into REM sleep, a stage where dreams are common. And we readily recall our dreams
when awoken from REM sleep. It is interesting that we cycle through the NREM-REM
sleep every 90-120 minutes so that 4-6 cycles are reported in adults during a night's
sleep. These cycles are numerous and short in infants lasting only about 50 minutes,
and 75 minutes in 2 yr olds, and 84 minutes in 5 yr olds.
Q6) What determines the time and the no. of hours
that we sleep?
A)We can easily identify 4 factors:
1. The inclination for sleep is the greatest when you have a large sleep need, ie.
the sleep pressure, for example when you previously had little sleep.
2. Your circadian rhythm (24-h biological clock) also dictates your sleepiness.
This internal clock is pretty accurate. That�s why for the normal sleeper, you are
ready for bed at a fixed time each night, and you wake up at around the same time
each day. But your clock can be shifted to a new schedule if you allow it.
3. The light-dark (day/night) cycle has a direct impact on the timing of the sleep-wake
cycle through melatonin, a hormone with a time keeping function. Following the onset
of darkness, melatonin, secreted by the pineal gland of the brain, promotes sleep.
Light suppresses the production of melatonin and holds back sleep.
4. The environment we live in plays an important role in our sleep-wake habits:
the type of jobs we do (shiftwork), the social or educational activities (playstation,
internet, parties, study) we engage in, all combine to determine the hours we stay
awake or asleep.
Q7) Some infants and children seem to have problems
going to sleep at night. What are the possible reasons for this and what's your
advice to parents to help their children overcome sleeping problems and establish
good sleeping habits ?
A)Very young infants sleep as much as they need. It is quite normal
for them to drift in and out of sleep. Feeding and sleep seem to be the major events
of their life at this age. Parents would be rewarded if they help establish good
sleep hygiene (ie. sleep habits) for their child. Poor sleep hygiene remains a major
factor causing sleeping difficulties.
Recommended good sleep hygiene:
• A regular routine of naps, bedtimes and feeding times, ie. you will need to keep
to these times almost all the time (despite your family social commitments!)
• Bed is for sleep only (no vigorous play or games, or "social" activities)
• As a child grows older, he has more wakeful periods in the day. Reduce the number
of naps, and shorten naps. A child may not be so inclined to go to bed early if
he has had plenty of sleep during the day.
Tips for sound sleep:
• Keep bedroom dark.
• Reduce noise level
• For the infant:
o comfortably wrapped (so neither too hot nor too cold)
o juggle feeding times to coincide with a late evening feed to encourage longer
sleep during the night, for example, an extra "snack" feed during mid-morning or
mid-afternoon may well put him back to nap again.
o From about 8 months of age discourage feeding just before bedtime and overnight,
as this tends to raise body temperatures and fragment sleep.
Some tips for coping with sleeping problems:
• For the child who has trouble in going to sleep at night Establishing bedtime
rituals such as the child being "tucked in", being read a story, or sung a lullaby.
This parental contact fosters good bedtime routine.
• For the child who wakes in the night Parents should know that waking up in the
night is not a "habit". It is not uncommon for children to wake up several times
during the night as they turn over. But they soon drop straight down to sleep again.
Children wake from sleep for a number of other reasons. They may be cold during
the wee hours of the morning if they are sleeping on top of the bedclothes. They
may be afraid of the dark when they do wake and need you. They may want their dummy
or cuddly bear if they can't find it.
A child may insist that you know all of his wakings, if you have made a habit of
going into his room whenever you hear a movement. You may actually be disturbing
his sleep!
Q8) What's your opinion of "rocking" or feeding as methods normally employed by parents to help their infants to sleep?
A)Rocking and other repetitive rhythmic behaviour (head-turning, head-banging
- as long as they don't hurt themselves) produce quieting and sleep. Other "self-soothing"
technique such as sucking the thumb or finger is equally effective in bringing on
sleep. Scientists report that rhythmic stimulation may reduce the occurrence of
sleep apnea (breathing cessation) and the associated slowing of the heart rate.
It is better for children to learn to fall asleep as independently as possible of
their carers. Over-involvement in the sleep onset routine may result in a child
needing attendance in the middle of the night, should the child wakes.
Q9) Most children experience nightmares in their
sleep. What are nightmares, why, and when (age of child and time of night) do they
usually occur? What can parents do to reduce or prevent the occurrence of nightmares?
A)Research shows that nightmares affect nearly half of every group
of toddlers studied. Most nightmares occur during deep sleep (stages 3&4 of
NREM sleep). Nightmares also arise from REM sleep. Some children wake up terrified.
But we do not know the content of their dreams. The occurrence pattern of nightmares
differs between children. Some have nightmares several times each night for a while
and then not at all for months. Others wake 3-4 times a week for several months
in a row. We don�t know what cause nightmares in children or adults. Nightmares
may be related to anxiety and stress. Love, fun and a set routine will give your
child the feeling of structured security, and would ease any strain, anxiety or
stress.
In dealing with nightmares, attend to your child as fast as you can the moment you
hear him crying. Cuddle your child and talk to him. He may need 15 minutes or more
to calm down. Night terrors are partial arousals from Stage 4 sleep. They are more
terrifying than nightmares. The children are inconsolable, screaming, often kick
or push their parents away and do not recall their dream contents when they wake.
Children often grow out of the night terrors by later childhood.
Q10) Some children snore in their sleep. Is this
considered normal or does it indicate breathing problems such as obstructive sleep
apnea syndrome? What can parents do to rule out the possibility of such problems?
A)The noise of snoring comes from the efforts to force air through
the narrowed air- passage. Whilst 10-30% of adults snore, the occurrence in children
is around 10% in different studies. Snoring is a risk factor for high blood pressure,
heart disease, stroke and sudden death, and a major symptom of obstructive sleep
apnea (OSA). Some observable features may allow parents to determine if their child
suffers from obstructive sleep apnea:
• loud snoring
• witnessed apneas
- plus struggling to breathe
• restless sleep
• sleeping in unusual positions
• excessive sweating at night
• poor weight gain
• bed wetting (after 6-7 years old)
• behavioural changes during the day - hyperactive or aggressive instead of sleepy
(only around 30% of children with OSA are sleepy as opposed to around 90% of adults)
Unlike adults, around 90% of children with sleep apnea will be cured by having their
tonsils and adenoids removed. Consultation with a sleep physician followed by a
sleep diagnostic study in a sleep laboratory, remain the gold standard investigation
for snoring and sleep-disordered breathing. This is because most studies have found
that history alone cannot differentiate between primary snoring (a noise problem)
and sleep-disordered breathing (a medical problem).