Rapid evidence
review on infant
and child sleep
June 2014
Laura Martin,
Ruth Chesser and
Dr Eileen Scott
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© NHS Health Scotland 2014
All rights reserved. Material contained in this
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While every effort is made to ensure that
the information given here is accurate, no
legal responsibility is accepted for any errors,
omissions or misleading statements.
NHS Health Scotland is a WHO Collaborating
Centre for Health Promotion and Public
Health Development.
This review reflects the information from the currently available literature. It should
be noted, therefore, that this comes from a limited number of articles and does not
necessarily deal with the wide range of experiences that parents have.
Key messages
•
In the early days and months, infants’ sleep is irregular and will take place
during day and night-time hours, slowly consolidating into the longest
sleep duration taking place over the night-time period.
•
There is wide variation in perceptions of normality – expectations are
shaped by numerous influences such as culture.
•
Parents who expect their child to sleep and place greater value on their
child sleeping through the night report higher levels of fatigue in
comparison with parents who expect frequent night awakenings in the
early parenting period.
•
Parental experiences of fatigue may undermine perceptions of parenting
competence.
•
Parent education programmes to enhance realistic expectations about
sleep and activity in the early parenting period are likely to help
understand variability, in order to reduce parental perceptions of relentless
fatigue.
•
Infants aged under six months experience significant physiological
changes which lead to self-regulation of sleep. Therefore, sleep training in
infants under six months is unnecessary, and may even be damaging to
the attachment process and establishment of breastfeeding.
•
Practitioners can play an important role in helping parents anticipate
continued night wakening by relaying that night awakenings constitute a
normative night-time experience especially for breastfeeding children. Also
that patterns change over time, often but not always, by six months of age.
•
Sleep behavioural interventions in older children did result in longer selfsustained sleep periods at an earlier age. However, these children did not
differ in independence in other domains from those who learnt to sleep
through the night at a later stage.
•
Some parents who implement sleep behavioural interventions can
experience difficulties in family functioning and in individual wellbeing.
Therefore, when advising parents about sleep interventions, practitioners
should seek to understand whether families’ parenting values fit their
night-time sleep practices.
•
Practitioners working with parents seeking sleep interventions can help
tailor a plan that helps to meet the parents’ needs and desires.
Glossary:
Infant: child between 0 and 1 year.
Sleep duration: period of time in sleep state.
Circadian process: Biological rhythm which develops to consolidate waking
into daytime hours and sleeping into night-time hours, often referred to as the
‘body clock’.
Sleep hygiene: pattern of behaviour to establish sleep; for example, no
television, vigorous exercise, stimulants, or heavy meals close to bedtime and
the use of sleep relaxation techniques, lavender spray, and white noise or
soothing music.
Independence domains: scale used to measure attainment of mature
behaviour in preschool-aged children in the domains of self-reliance in daily
living skills and social independence.
Introduction:
Parents often rate children’s sleep problems as more stressful than health problems
(Henderson et al, 2010). They report concerns about whether their child’s sleep
pattern is age-appropriate, problematic and more specifically wonder when they will
‘sleep through the night’ (Henderson et al, 2010).
Sleep–awake patterns are formed through a complex interaction between biological
processes and environmental, behavioural and social factors. This could involve the
infant’s genetic make-up, day care schedules, family routines as well as parental
expectations (Galland et al, 2011).
Studies have shown that western society norms of having infants sleep alone in a
separate room have led to an increase in cortisol levels in children and an increase
in infant night crying when compared to children who sleep in close proximity to their
parents (Waynforth, 2007). Disruption in adult sleep, which can impact for example
on areas of parents’ lives such as performance in the workplace, has resulted in
pathologising the behaviour and the communication of infant crying as abnormal or
at least unacceptable. (Blunden et al, 2011).
There is a question about whether infant night awakenings are a sleep problem or a
symptom of the infant’s psychological need to know their parents or caregivers are
close by. In order to support parents in the earlier days and years, it is important that
we understand what is normal infant and child sleep and how best to encourage
positive infant and child sleep.
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Rapid evidence review
The key questions that this review sought to address were:
•
What is known about normal infant sleep?
•
What is known about the impact of sleep deprivation on the ability of parents
to provide responsive care?
•
What are the most effective ways to establish and/or improve infant/child
sleep patterns?
Studies defining normality do not necessarily describe wide variability that equates to
parents’ experience. Babies differ in part for reasons explained in this report. Babies
adopt settled night-related sleep over a range of time – some early in life, and some
later.
The terms unsettled, night awakenings and night crying are used to denote a baby’s
inability to self-settle or self-sooth; i.e. to transition into sleep or back to sleep in a
separate sleeping space without parental intervention.
A total of 16 relevant papers were identified, and each paper was critically appraised.
This paper presents a synthesised summary of this evidence.
What is known about normal infant sleep?
This rapid evidence review looked at systematic reviews and reviews of reviews
which explored what is known about normal infant sleep patterns, including:
•
•
•
•
changes to sleep patterns over the first few years
longest sleep period
longest self-regulated sleep period
‘sleeping through the night’.
In order to be able to support parents on their child sleep-related developments, it is
important to establish what is known about ‘normal’ infant sleep patterns.
Research methods used in included studies:
Studies researching normal infant-sleep patterns are often limited due to the
methods used (observational studies or subjective, self-report data). Information is
gathered largely through sleep diaries or questionnaires completed by the parent or
caregiver. This can result in overestimating sleep duration as times going to bed and
rising are reported (Galland et al, 2011) as opposed to actual sleep duration.
Actual sleep duration would be ascertained through physiological measures
including polysomnography, actigraphy and videosomnography. However, these
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methods can disrupt sleep and therefore are not commonly used in infant and child
sleep studies.
Changes to sleep patterns:
A systematic review (Galland et al, 2011), explored normal sleep patterns for
children aged 0–12 years including findings from studies conducted after 1990.
Sleep patterns show a wide range in infancy with developmental trends for
increasing sleep duration, with the greatest rate of change occurring within the first
six months. During these first six months after birth, most infants develop the ability
to sustain longer episodes of sleep and begin to consolidate sleep towards the night
time. This reflects the sleeping patterns of adults (Galland et al, 2011).
The maturing of the circadian process at around two to three months of age is
associated with the most significant changes in the duration (sustaining longer
periods of sleep) and timing of infant sleep (consolidation of sleep to occur during
night-time hours) (Crabtree, 2009). This process is often referred to as the ‘body
clock’ and as this matures it begins to set a regular sleep–wake rhythm over a 24
hour period. This developing pattern continues up to the age of 2.
The number of night-time awakenings reduces between the ages of 0–2 years with
the longest sleep period (longest duration of sleep without waking and calling out for
parental intervention) increasing during this age range (Galland et al, 2011), with the
number of daytime naps decreasing. It is often reported that this decrease in daytime
naps accounts for the greatest change in total sleep duration during infancy
(Crabtree, 2009).
Limitations identified by the review include a lack of evidence on normal sleep for
toddlers, recording of any gender differences and weekday versus weekend sleep
patterns.
Sustained sleep:
A recent review investigated the changes in infants’ capabilities for sustained sleep
across their first year (Henderson et al, 2010) with the aim of establishing the
normative developmental course of sleep and self-regulated sleep in typically
developing infants within their first year of life.
In order to determine when infants consolidate their sleep, begin to sleep through the
night and coordinate their sleep within the family sleep patterns, three aspects of
sleep were reviewed:
•
The longest sustained sleep period (LSP) – this is the ability to sustain a long
period of unbroken sleep.
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•
Longest self-regulated sleep period (LSRSP) – this includes episodes of both
sleep and quiet wakefulness with the infant’s ability to independently reinitiate
sleep.
•
‘Sleeping through the night’ – this describes the ability of an infant to sleep
uninterrupted during a predetermined nocturnal period.
The above review found that infant sleep, regardless of longest sustained sleep
period or longest self-regulated sleep period, consolidates rapidly in the first few
months. This finding is in agreement with Galland (2011), with both reviews reporting
that the most marked rate of change occurs between the ages of one and two
months. Sleep consolidation (consolidation of sleep during night-time hours) peaks
at three months and tapers off thereafter.
In relation to longest sustained sleep period, the greatest rate of change took place
within the first three months, and particularly between the ages of one and two
months (Henderson et al, 2010). This period of sustained sleep is then maintained
up until around 1 year. The findings suggest that an infant’s longest sustained sleep
period is strongly determined biologically, with little variability between studies,
across time or populations, indicating that infants share a similar capacity to sustain
sleep. In contrast, capacities for self-soothing and other aspects of sleep regulation,
and the timing of sleep periods, were found to be more environmentally determined
(Henderson at el, 2010).
Longest sustained sleep periods (more than five or six hours) may be the precursor
for increases in the longest self-regulated sleep period. The longest self-regulated
sleep period was found to have a similar rapid rate of change over the first four
months and then also levels out until around nine months, after which it again begins
to increase.
There was a similarity in the time it takes for infants to meet the criteria for sleeping
through the night (sleep period of six hours or more) in the first four months. Infants
can sleep around eight hours by the age of six months and increase to nine hours or
more after this age milestone (Henderson et al, 2010).
However, findings are limited by inconsistent approaches to definitions, age ranges
of infants and variation in the study methodologies adopted by the single studies
incorporated within the review.
What is known about the impact of sleep deprivation on the ability of parents
to provide responsive care?
No systematic review-level evidence was identified to answer this question.
However, there are a number of single studies that look into the effects of infant and
child night awakenings on parents’ ability to provide responsive care to their children.
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The following provides a summary of the findings across these studies; as these are
single studies, the following findings should be treated with caution.
Sleep in postpartum women
A selective review of postpartum sleep in women found that, on average, total sleep
is reduced to between 6.34 and 7.53 hours in women studied up to five months
postpartum from seven to nine hours per day for ‘normal’ adult sleep (Hunter et al,
2009).
This review also found that women’s postpartum sleep contains more sleep
awakenings with an increased amount of stage 1 sleep (when most easily
awakened) and a reduction in the amount of REM and stage 4 sleep (characterised
by difficulty in awakening individual) leading to decreased sleep efficiency (Hunter et
al, 2009).
The most common causes of sleep disturbance are directly related to newborn care,
specifically feeding and sleeping patterns (Hunter et al, 2009).
First-time mothers and mothers who gave birth via C-section appear to be at greater
risk of disturbed sleep than women who have had their second child or given birth
naturally (Hunter et al, 2009).
Impact of sleep disturbance
Infant night awakenings increased fatigue, depression, anxiety and stress among
parents. Unrealistic expectations about maternal sleep and activity, and a perceived
need for more social support were the strongest predictors of fatigue in parents
(Giallo et al, 2011 Hunter et al, 2009, Rolls & Hanna, 2001).
In studies that included the impact of night awakening on both the father and the
mother, an association was found between infants’ and young children’s night
awakenings and both parents’ experiences of fatigue. However, within the same
family, mothers experienced more daytime sleepiness than fathers, although sleep
duration was similar. This seemed to be due, in the most part, to mothers providing
the majority of care during the night and therefore experiencing a greater amount of
sleep disruption (Giallo et al, 2011, Boergers et al, 2007).
However, it should be noted that the studies mostly involved samples of parents
attending sleep clinics (Giallo et al, 2011, Boergers et al, 2007, Rolls and Hanna,
2001), who had sought professional support due to infant sleep problems. Therefore
it is plausible to suggest that these samples may show greater effects of sleep
disturbance on parental behaviours.
Experience of fatigue may make it harder to use coping skills and resources to
manage feelings of depression, stress or anxiety. However, it is also possible that
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the physical symptoms of anxiety and stress and depression may contribute to the
mental and physical experience of fatigue (Giallo et al, 2011
In a number of studies, tiredness was reported by parents to get in the way of the
parent they would like to be, with high levels of fatigue associated with low parenting
efficacy and satisfaction (Giallo et al, 2011, Hunter et al, 2009, Rolls and Hanna
2001).
Experience of fatigue may undermine perceptions of parenting competence. Mothers
who reported high levels of fatigue indicated that they were more likely to engage in
hostile parenting behaviour such as using a raised voice, losing their temper with
their child or feeling angry. Such reactions in exhausted parents can be explained by
the research indicating that cognitive fatigue can have a negative impact on
emotional regulation, impulse control, and frustration tolerance and management
(Giallo et al, 2011).
A selective review (Hunter et al, 2009) suggested a relationship between poor sleep
and depression. Depressed mothers identified significant sleep related factors:
•
•
•
•
•
sleep disturbance
decreased sleep duration
perception that infant care performance was affected by daytime sleepiness
trouble falling asleep
waking earlier.
However, it was recognised that this causation relationship could be reversed, with
sleep deprivation and fatigue being a symptom of depression.
Support for parents
Expectant parents and new parents may benefit from information about the potential
effects of fatigue on their functioning and parenting behaviour as well as practical
strategies for the management of frustration and stress. Parent education
programmes to enhance realistic expectations about sleep and activity in the early
parenting period are likely to reduce parental perceptions of fatigue (Giallo et al,
2011).
Prenatal education should emphasise information on improper and proper sleep
hygiene that has proven effective in the general population: avoidance of television,
vigorous exercise, stimulants and heavy meals close to bedtime and the use of sleep
relaxation techniques, lavender spray and white noise or soothing music (Hunter et
al, 2009).
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What are the most effective ways to establish and/or improve infant/child sleep
patterns?
A number of systematic reviews and single studies have looked at effective ways to
establish and/or improve infant sleep patterns. The systematic review evidence
covers infants from birth to six months. Only single-study-level evidence is available
from children over the age of six months. Therefore this paper will review separately
the findings into infants (between birth and six months) and children (between the
ages of six months and 5 years). As findings for children between the ages of six
months to 5 years are from single studies their conclusions should be treated with
caution.
Birth to six months
Behavioural interventions for infant sleep are defined as a parental practice or infant
care method that aims to train the infant’s neurobiological characteristics so that
nocturnal self-settling episodes are more common. These include delayed response
to infant signals or cues, regulation of feed times, algorithms for sleep durations and
bedtimes and other strategies that aim to condition the infant to fall asleep in the
absence of feeding or bodily contact with carer (Douglas and Hill, 2013) .
A systematic review looking at behavioural interventions for sleep applied by parents
to infants younger than six months found no increase in sustained infant sleep
periods or night awakenings over the period of time of the study significantly beyond
what would be expected due to normal neurological development (Douglas and Hill
2013).
Unintended outcomes of behavioural interventions for infants under six months
included:
•
premature cessation of breastfeeding (due to impact on milk supply as a
result of lack of night-time feeding)
•
increased crying
•
inhibited consolidation of sleep at night
•
parental misreading of baby cues.
(Douglas and Hill, 2013)
Behavioural sleep interventions in the first six months did not decrease rates of
postnatal depression (Douglas and Hill, 2013) .
Early sleep interventions result in parents being focused on infant sleep frequency
and duration, on the number of night-time wakenings and on potential negative
effects on their life and the infant’s life. In adult sleep therapy, focusing on these
cognitions has been demonstrated to reinforce adult sleep anxiety, worsen sleep
8
efficiency and worsen subjective feelings of sleep deprivation (Douglas and Hill,
2013).
Strategies to support parents include education about sensible cue-based care;
about healthy daytime biopsychosocial rhythms; by addressing parental sleep
anxiety, safe sleep and normal crying and by the prevention of, and early
intervention for, the heterogeneous problems including feeding difficulties and
psychosocial risk factors which are linked to the emergence of unsettled infant
behaviour (Douglas and Hill, 2013).
Additional studies found mothers may have better sleep if the newborn is allowed to
sleep in close proximity (Hunter et al, 2009, Blunden et al, 2011).
Six months to 5 years
One study found an association between parental nocturnal involvement and infant
sleep problems. In the study group, infants who fell asleep in their crib with minimal
parental assistance had fewer night awakenings than infants who fell asleep with
significant parental involvement (while being held, fed, rocked, etc.). However, as the
study noted, this could be attributed to reverse causation, where infants with more
difficult sleep patterns require more parental involvement (Sadeh et al, 2010).
Socio-cultural setting plays a role in shaping parental expectations and parenting
styles. Expectations and parenting practices regarding infant sleep and whether
certain behaviours, i.e. night wakening, are perceived as problematic vary according
to cultural norms, ethnicity and socio-economic background (Sadeh et al, 2010).
A study from birth to 36 months found that the most common attempts to initiate
sleep are falling asleep in the parent’s bed with a parent present and feeding to
sleep. Less frequent behaviours are falling asleep without parental intervention or in
a crib/bed with the parent present. Falling asleep independently was linked to longer
sleep duration and fewer night wakenings but as the study by Sadeh et al, shows, it
was noted that this is not proof that there was a cause and effect relationship
(Mindell et al, 2010).
A study of children aged 36–69 months found that sleep arrangements and the
importance placed on sleeping through the night were the strongest contributors to
variance explained in whether children learned to sleep through the night during
infancy or toddlerhood. Mothers of solitary sleepers valued an earlier stage of
sleeping through the night and in actual practice did have children who slept through
the night at an earlier stage. However, this achievement did come at some cost, as
mothers who placed greater value on their children sleeping through the night early
(during infancy) also reported greater difficulties in family functioning and in
individual wellbeing during this period. When advising parents about sleep
interventions, practitioners should seek to understand whether families’ parenting
9
values and the importance parents place on children sleeping through the night fit
their recommended night-time sleep practices (Germo et al, 2009).
A lack of independence in establishing sleep, for example requiring parental support
to fall asleep, does not appear to generalise to dependence in other domains such
as self-reliance in daily living skills and social independence. The results suggest
that compared to their counterparts who learned to sleep through the night at an
early age, children who learned to sleep through the night at a later stage did not
differ in domains of independence at the preschool stage (Germo et al, 2009).
A study on the macronutrient composition of the evening meal for children who were
2 years old found that a high percentage of total daily energy intake with the evening
meal, particularly from carbohydrates, along with the replacement of protein by high
GI carbohydrates in the evening meal is accompanied by a slightly longer mean
sleep duration in toddlers (Diethelm et al, 2011)
An intervention study on children between the ages of 3–5 years found that the
viewing of media with violent content (TV, DVDs, gaming, etc.) throughout day
increased sleep problems, with a change to pro-social and educational content
resulting in reduced sleep problems in the intervention group (Garrison and
Christakis, 2012).
Supporting improved sleep outcomes
Practitioners can play an important role in helping parents to anticipate continued
night wakening by relaying that night wakening constitutes a normative night-time
experience. Sleep patterns in the majority of children will naturally settle over time as
the child develops and implementing plans to try to influence this process have
limited success.
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