Background/rationale
It is important for care providers who are promoting healthy sleep for infants and toddlers to be familiar with empirical data to inform their areas of assessment. The background/rationale section provides information about the complexities of factors to consider when assessing sleep. Then, we review various methods of assessing sleep among infants and toddlers, providing suggestions for assessments in different contexts (e.g., primary care, sleep specialist).
Sleep and feeding
There is a complex relationship between feeding and sleep from the outset of infancy. Starting as early as 6 weeks post birth, infant-only night waking (i.e., waking but not signaling parents) increases over the first 24 weeks of life; the presence of infant-only wakes is associated with a faster rate of decline in infants’ night-time feeds from 6 to 24 weeks.
Breastfeeding tends to relate to shorter night sleep durations. Portuguese infants who were exclusively breastfed at 3 months had shorter longest sleep period at night when ages 3 and 6 months, compared to exclusively formula-fed infants. In an Asia-Pacific region study, breastfed infants at less than 6 months of age had increased number and duration of night waking and less consolidated sleep; however, breastfeeding at less than 6 months of age was related to longer duration of daytime sleep and more sleep overall.
A French longitudinal study examined feeding at 4 months, 8 months, and 1 year and sleep quantity and quality trajectories at ages 2, 3, and 5 to 6 years. There was no association between the use of thickened baby formula, or age of introduction of complementary foods or baby cereal, and persistent sleep onset difficulties. Infants predominantly breastfed for more than 4 months were less likely to belong to the persistent sleep onset difficulties trajectory. Early introduction (<4 months) to complementary foods, excluding baby cereals, was related to lower risk of belonging to the short-sleepers trajectory.
A key issue is feeding at night. Night feeding, in infancy or at 2 years, has been associated with higher risk of persistent sleep-onset difficulties between 2 and 5 to 6 years old; night-feeding at 8 months was related to a higher risk of persistent night-waking over time and short-sleep between 2 and 5 to 6 years of age. In a cross-sectional study, breastfed infants (6–12 months of age) who were also breastfed back to sleep during the night woke more frequently at night and had shorter continuous nighttime sleep periods.
Conclusion
It is important to explore the type of infant feeding (e.g., breast, bottle) at the time of assessment including the timing of feeding before the start of nighttime sleep and timing of feeding during the night. The fit with feeding over 24 hours and the developmental stage of the infant needs to be considered. Pay particular attention to whether or not the child’s sleep onset occurs during/at the end of a feeding.
Sleep and safety
Highly developed countries around the world have guidelines about infant sleep position and safety practices to reduce sudden infant death (SID). In particular, there is wide consensus around key preventive factors including: (1) supine positioning; (2) firm and flat sleep surfaces; (3) minimal coverings and clothing; (4) low room temperature; (5) nonexposure to smoking; (6) parental avoidance of alcohol, sedating medications, and illicit drugs; and (7) nonshared sleep surfaces. In addition to SID, there is also sudden unexpected death in infancy: deaths of “well” infants for whom cause of death is not obvious, with external risk factors that may have contributed to the death. Risk factors include: (1) suffocation due to soft bedding, (2) overlay, by another person, and (3) wedging.
Considerable empirical data has indicated that many parents have difficulty adhering to safe sleep guidelines, in particular following supine positioning and avoiding bedsharing. , , Those findings have resulted in some jurisdictions incorporating harm reduction strategies in guidelines for health care providers and parents, such as preparing a safe bed for healthy full term breastfeeding infants.
In contrast to infants, there are limited data about toddlers and sleep safety. Scheers and colleagues (2019) reported maternal assessment of infant and toddler injuries associated with crib-bumpers and mesh liners, versus no barriers. Injuries included face covered, climb-out and falls, slat entrapment, and hitting head. Crib bumpers had higher risks of face covering, breathing difficulties, and wedging. Climb-out and falls were not associated with any of the crib arrangements. For toddlers who are walking, it is important for parents to consider gates on bedroom doors to avoid toddlers accessing stairs or other hazards during the night. Locking bedroom doors is not recommended due to safety hazards in the event of situations such as a fire.
Conclusion
It is important to incorporate questions about sleep safety when undertaking a sleep assessment, as is recommended by multiple organizations. For example, the Academy of Breastfeeding Medicine has recommended that health care providers counsel all families about children’s safe sleep, including elements of safe bedsharing advice, hazardous circumstances during bedsharing, and risk minimization strategies for families where bedsharing is high risk (e.g., referral for smoking cessation and alcohol and/or drug treatment ). It is important for care providers to be open to listening to parents’ difficulties following proscriptions and consider harm reduction principles.
Sleep time
Total sleep time
Despite some controversy about recommending sleep duration ranges for children, two organizations have created documents with recommendations. Table 13.1 presents the recommendations from the National Sleep Foundation and the American Academy of Sleep Medicine. The National Sleep Foundation acknowledges that, although sleep and/or time-in-bed duration represents a major dimension for measuring sleep, other indices important to consider are sleep quality, sleep architecture, and the timing of sleep within the day.
| Age | National Sleep Foundation 1 | American Academy of Sleep Medicine 2 | 24-Hour Movement Guidelines (Canada) 3 | |||
|---|---|---|---|---|---|---|
| Total Sleep—24 hours | Minimal | Maximal | ||||
| Newborns | 0–3 months | 14–17 hours | Not less than 11 | 19 | No recommendation | 14–17 hours |
| Infants | 4–12 months | 12–15 hours | Not less than 11 | 19 | 12–16 hours | 12–16 hours |
| Toddlers | 1–2 years | 11–14 hours | Not less than 10 | 18 | 11–14 hours | 11–14 hours |
1 Hirshkowitz M, Whiton K, Albert SM, et al. National Sleep Foundation’s updated sleep duration recommendations: final report. Sleep Health . 2015;1(4):233–243.
2 Paruthi S, Brooks LJ, D’Ambrosio C, et al. Recommended amount of sleep for pediatric populations: a consensus statement of the American Academy of Sleep Medicine. J Clin Sleep Med . 2016;12(6):785–786.
3 Tremblay MS, Chaput JP, Adamo KB, et al. Canadian 24-hour movement guidelines for the early years (0–4 years): an integration of physical activity, sedentary behaviour, and sleep. BMC Public Health . 2017;17(Suppl 5):874.
Naps and sleep consolidation
A study of American children between birth and age 36 months, using an iPhone app, identified sleep consolidating into two naps of about 1.5 hours in length and a night-time sleep session of about 10.5 hours occurred between 3 and 7 months of age. Naps varied with age, decreasing between 1 and 5 months old and then increasing monotonically through 28 months. Between 12 and 24 months, only about 2.5% of children will cease napping and switch to monophasic (night only) sleep. It is critical to reinforce the need for naps among young children.
Sleep duration varies across families
One study examined racial/ethnic and socioeconomic differences in objectively measured sleep-wake patterns between 1 and 6 months of age among American infants using actigraphy. Changes in nighttime sleep duration from age 1 to 6 months varied by race: White infants’ sleep duration increased by 82 minutes, while Hispanic infants increased by 49 minutes and Black infants increased by 32 minutes. In general, Hispanic/Latino, Asian, and Black infants or infants from lower SES families had less consolidated and shorter 24-hour sleep; for daytime sleep duration at 6 months of age, Hispanic-Latino, Asian, and Black infants had longer daytime sleep duration. Nighttime sleep duration also varied, with lower maternal education and lower household income related to shorter sleep. In addition, after adjusting for maternal education and household income, Asian infants had more frequent wakes and reduced nighttime sleep at 6 months.
Conclusion
Sleep time varies considerably based on individual differences. Nevertheless, it is important to consider if an infant/toddler is sleeping outside of the range of recommended sleep times.
Sleep associations and routines
Sleep associations are particularly important for infants and toddlers. Sleep associations refer to the conditions present at sleep onset, including presence of parents, toys, other objects, playing music, etc. When sleep onset is paired with a specific set of conditions, children can quickly become dependent on having these conditions in order to sleep, which can contribute to signaled night waking. Thus, when an infant is fed or rocked to sleep and then put in the crib, they will struggle to fall asleep independently when they wake at night.
In contrast to negative sleep associations, sleep hygiene refers to behaviors conducive to adequate sleep duration and quality, including sleep schedules, sleep habits, and sleep environment. A systematic review examined sleep hygiene for infants, toddlers, and older children. For infants and toddlers, bedtime routines (regular activities such as reading and brushing teeth) and independently falling asleep (self-soothing) are related to increased sleep duration, decreased sleep onset latency, and reduced night waking.
Another systematic review examined sleep-wake behavior in the first 12 months of life. Lack of bedtime routines and more television and media exposure before bedtime related to poorer sleep, that is, shorter nighttime sleep duration and more night wakes. Establishing positive routines when children are young sets a foundation for good sleep as children develop. For example, a longitudinal study of American children found positive activities in the hour before bed (e.g., reading a story, cuddle with a caregiver) at 3 months predicted longer sleep duration at 12 months of age; these bedtime activities at 12 months of age predicted fewer sleep problems at 18 months.
Conclusion
Whenever a health care provider is assessing infant and toddler sleep it is critical to examine sleep associations. Assess both negative sleep associations and positive routines and behaviors that facilitate sleep.
Sleep environment
Light levels are an important consideration when assessing infant and toddler sleep. Light is considered one of the most powerful factors in synchronizing the circadian sleep/wake rhythm to the 24-hour day and particularly important for infants developing this synchronization between 2 and 10 weeks of age. Tsai and colleagues (2012) found that 2- to 10-week-old infants spent the majority of their time in low light settings and had only brief exposure to bright light settings over 7 days. Harrison (2004) found that 6- to 12-week-old infants who slept more during the night were exposed to significantly more light during the afternoon.
Data on light and infant sleep are limited. Among preschool age children (3–5 years), bright light (>1000 lux; considered bright outdoor light) exposure in the hour before bed induced a 90% suppression of melatonin assessed by saliva, and melatonin suppression remained high for 50 minutes following exposure. , Melatonin suppression would tend to delay nighttime sleep onset. Further, children may be more sensitive than adults to light before bed, although no data are available for infants.
Artificial light at night (ALAN) may also play a role in night-time sleep, although research is limited and mixed. Higher levels of ALAN may be related to later bedtimes and complaints of disrupting sleep in older samples (ages 8–18). No studies of infants or preschool-aged children have been identified.
Mold and water damage are risk factors for wheezing in infants, even after controlling for dust mite exposure, and wheezing may impair sleep. For infants prone to allergies, risk of wheezing when mold or water damage was present was five times greater (compared to no mold/water damage). Given the amount of time infants spend in their sleep environments, assessment of environmental exposures is critical. Due to lower weight and smaller size, contaminant exposures (from mattresses, sheets, cribs, etc.) may pose a heightened health risk to infants compared to older children and adults.
Noise in the home and neighborhood (e.g., traffic, sirens) may also impact children’s sleep. A number of qualitative studies have investigated parent-identified barriers to infant and preschool sleep in multiethnic samples. For example, Sanler and colleagues interviewed parents of infants (aged 3–36 months) and pediatric health care and childcare providers. Neighborhood and in-home noise were noted as barriers to sleep by all reporters. A longitudinal study by Blume and colleagues investigated the relationship between night-time transportation noise and infant sleep (via actigraphy) over an 11-day period at ages 3, 6, and 12 months. Overall, night-time transportation noise did not significantly predict sleep outcomes (i.e., sleep duration, activity, and variability). However, there was a significant interaction between having siblings in the home and transportation noise; infants without siblings were more sensitive to transportation noise than infants with siblings who have habituated to louder conditions.
Material hardship: Environmental factors associated with poor sleep tend to cooccur. Thus, socio-economic factors are also important to note when assessing sleep in infants. A longitudinal study by Duh-Leong and colleagues (2020) investigated the relationship between financial difficulty, food insecurity, housing disrepair and multiple hardships and sleep duration in a sample of Hispanic families. Financial difficulties, multiple hardships and housing disrepair were associated with poorer sleep duration in 3-month-old infants. Mechanisms linking hardship and child sleep also include psychosocial factors. Increased stress in the household as a result of financial difficulties, multiple hardships or housing disrepair may disrupt parent night-time sleep and shorten night sleep in infants.
Conclusion
Health care providers should incorporate environmental considerations in their assessments of infant and toddler sleep; there is a need to move beyond the focus on individual child- and parent/family-factors to consider how the immediate (e.g., bedroom) and housing (e.g., neighborhood) environment may enhance or interfere with sleep. Many of these factors can be targeted with interventions (e.g., black out curtains, use of a fan for white noise), so assessing the impact of these factors on sleep may be important.
Sleep and screen exposure
Attention is increasingly being directed to the relationship between children’s screen exposure and sleep. There are four aspects of sleep and screen time to consider.
- (a)
Screen time is common: Among Singaporean children between 0 and 2 years, 53% had daily screen viewing, with a higher prevalence of TV viewing (44.3%) and mobile device viewing (30.1%) than computer time. Children were exposed to a median of 1 hour of screen viewing per day; TV median time was 0.98 hours per day and mobile devices and computer viewing 0.50 hours per day.
- (b)
Screen time increases with age: Among older children (7–24 months), 73% had some screen viewing within a 24-hour period, compared to 28% of children 6 months or younger.
- (c)
More screen time is linked to more sleep problems: Moorman and colleagues (2019) conducted a systematic review of effects of screen time on children’s sleep between 1 and 5 years of age. They reported that greater consumption of, access and exposure to, and engagement with screen media were associated with shorter nighttime and total sleep duration, poorer sleep quality, later bed times and wake times, and longer time for sleep onset. Similar findings exist for infants.
For 3-month-old infants, 5 minutes of daytime touchscreen exposure was associated with an average decrease of 13 minutes in daytime sleep, while about 34 minutes of TV exposure was associated with a 20-minute decrease in daytime sleep duration. TV exposure also impacted 24-hour sleep duration. On average, 34 minutes of TV exposure was linked to a 22-minute decrease in 24-hour sleep duration. Among children aged 6 months or less, compared with no screen viewing time, screen viewing up to 1 hour related to 1.5 hours shorter total sleep duration, and viewing of 2 or more hours per day was associated with almost 3 hours of shorter sleep duration. In addition, more daytime touchscreen exposure was associated with fewer night wakes for infants, but was associated with more night wakes for 13 month olds. Increased evening/nighttime touchscreen exposure was also associated with increased daytime sleep duration in younger infants. Similarly, a study by Chen and colleagues (2019) found that for every hour of screen time in Singaporean children (aged 0–2), sleep duration was significantly decreased by approximately 16 minutes. Among 7 to 24 month olds, screen times of 1 to 2 hours were associated with 0.84 hours less sleep, and 2 or more hours was related to 0.91 hours less total sleep duration.
- (d)
Screen time varies across families, as does its impact: In a systematic review, more robust associations between screen media use and negative sleep outcomes occurred for: (1) boys and (2) racial and ethnic minorities. Similar associations were found among children with families characterized by: (1) larger size, (2) parents who work long hours, (3) lower income, (4) less educated parents, (5) single parent households, (6) and urban residence.
On the other hand, lower daytime and evening/nighttime screen exposure occurred among younger infants who (1) shared a room with parents, (2) were breastfed, and (3) had highly educated parents. Black infants also tend to have longer evening/nighttime screen exposures. A Canadian study recruited children from daycare settings (as such children had no/minimal exposure to screens during this time) and found that parents’ higher education and income related to longer sleep duration. Even though children were in childcare during the day, an increase of 1 minute per day in total screen time (e.g., TV, video game) was associated with a decrease of 0.2 minutes per day in nighttime sleep duration.
Conclusion
The ubiquity of children’s exposure to screens and relationships between infants’ and toddlers’ exposure to screens and sleep problems emphasizes the importance of health care providers’ incorporation of questions about the nature and duration of screen time in assessments of infants’ and toddlers’ sleep.
Bedsharing
Parents’ and infants’ bedsharing, defined as sharing a sleeping surface, remains a controversial area of sleep research. In a narrative review, Mileva-Seitz et al. (2017) distinguished between proactive (or intentional) and reactive (in response to child distress, protests) bedsharing. Families who proactively bedshare tend to take into account safety (e.g., pay attention to potential risks associated with bedding). In contrast, reactive bedsharing involves spontaneous introduction of an infant to the parental bed and safety issues that may result. Volpe and Ball (2015) argued that parents intentionally bedsharing attended to potential risks. Mileva-Sietz et al.’s review indicated that bedsharing was widely associated with older infant and child sleep problems including frequent night-waking and/or time spent awake at night, nighttime crying, requests for comfort and getting out of bed at night, nightmares, and less nighttime sleep. For example, a large Norwegian study of nocturnal sleep duration and waking in infants from 6 to 18 months of age found bedsharing at 6 months predicted more frequent night waking and short nighttime sleep duration at 18 months of age.
Conclusion
Health care providers’ awareness of empirical evidence about bedsharing should inform assessments of children’s sleep problems. In particular, inquiry about proactive versus reactive bedsharing and attention to safe sleep conditions are important considerations for effects on caregivers and children.
Parent factors
Sleep behaviors
Parent sleep behaviors (e.g., sleep duration, sleep schedules) have been linked to child sleep in a number of studies of school-age and adolescent children. These behaviors include attention to children’s sleep hygiene, as well as timing and duration of children’s sleep. Research on infant sleep has examined how sleep architecture (such as persistent, regular, and lengthy night waking) in infants impacts maternal/parental sleep. Lack of extensive empirical work about effects of parents’ sleep on infants represents an important gap in our understanding of infant sleep.
Parents’ mental health
Parents’ mental health has largely been linked to parental perceptions of infant sleep problems, rather than infant sleep per se. There is difficulty, however, in determining whether parents’ mental distress precedes infants’ and toddlers’ sleep problems, or whether children’s sleep problems produce parental distress. For example, Tikotzky and colleagues (2021) studied Israeli mothers longitudinally from the third trimester of pregnancy to 18 months post birth. High maternal distress related to perceptions of children’s sleep as problematic. However, from pregnancy to 18 months, changes in maternal emotional distress did not predict changes in infants’ objective sleep.
Nevertheless, parents’ distress and perceptions of their child’s sleep are linked with parents’ perceptions of sleep problems. In mediation analyses, Teti and Crosby (2012) found maternal depressive symptoms and dysfunctional cognitions about infant sleep behavior (worries about infant physical/emotional needs) led to maternal presence during the night and in turn higher levels of infant night waking. A study of Canadian mothers and 6-month-old infants found that mothers with higher levels of depressive symptoms and who perceived their infants as having more negative affect reported the most problematic infant sleep. An Israeli intervention study found parents’ reactivity to infant crying affected responses to using camping out (i.e., parents sitting in child’s sleep space without contact) or checking in (i.e., parents entering the child’s sleep space briefly). Higher parental tolerance for crying at baseline predicted larger reductions in the number of infants’ nighttime awakenings and greater improvement in parent-reported sleep.
Conclusion
Any assessment of children’s sleep requires an understanding of the family context and dynamics. In particular, attention should be paid to how parents create conditions for children’s sleep and the psychological effects of children’s sleep on parents.
Family factors: Family structure/coparenting/marital conflict
The literature specifically examining differences in family structure on sleep among infants and toddlers is sparse. An Israeli study found no differences in infants’ or mothers’ sleep (by actigraphy and diaries) between single mothers by choice and two-parent families. Studies have examined whether infant sleep predicts coparenting (i.e., how parents work together, , but not whether coparenting predicts infant sleep. An important contribution of these studies has been to document how disagreements between parents regarding responding to infant night-waking leads to worse perceptions of coparenting over time. Similarly, children’s sleep problems have been shown to predict poorer marital relationship. , Reciprocal effects are also evident; that is, marital conflict is predictive of children’s sleep problems. ,
Conclusion
Although data are limited, a basic understanding of family structure/dynamics is essential in any assessment. Attention to how parents work together, or have conflict, with respect to their infant’s sleep is also important, as is an understanding of how infant sleep may be affecting coparenting and the parents’ relationship.
Assessment methods
Recommendations for assessment methods are presented first for situations in which a brief assessment is needed; these methods may be relevant for primary care physicians/nurse practitioners or other general health/mental health providers. For example, when a child is being assessed for possible mental health or developmental issues, a provider may wish to screen for sleep-related issues. Second, we provide recommendations for more detailed assessments, which might be relevant when a family is seeking help specifically for their child’s sleep issues or when screening suggests more detailed assessment is warranted. Finally, we provide suggestions for a sequenced approach to an in-depth assessment. A recent review noted that there is currently a very limited evidence base when it comes to specific measurement tools for sleep in young children. As such, our recommendations are based on the extant literature and our clinical and research expertise.
Brief-screening methods
Items assessing parent perceptions of a sleep problem
If clinicians are using brief questionnaires as part of an assessment, there are some sleep-related items that may be useful to include. Parental endorsement of one or two items related to sleep issues would warrant further screening questions.
A recent study of parents of young children (5–19 months) in a pediatric primary care setting examined the utility of using screening items asking about parental perceptions of sleep problems and night waking. However, they were unable to develop an optimal set of items that was both sensitive and specific compared to the Brief Infant Sleep Questionnaire (BISQ). Items asking about parent perceptions of a sleep concern/problem (“Do you think [child’s name] has a sleep problem”) identified about a third of cases who had a clinically significant score on the BISQ. In contrast, items about night waking (“Does [child’s name] often wake up one or more times in the night and does an adult go to [HIM/HER]?”) appear to identify too many children (68%) as having sleep problems.
One widely used screening item is from the BISQ. The item asks, “Do you consider your child’s sleep a problem?” with four response options: 0 ( no ), 1 ( yes, mild ), 2 ( yes, moderate ), to 3 ( yes, severe ). This item has been used in numerous studies (e.g., Mindell et al., 2010 ). In light of findings from the Honaker et al. (2021) study, we recommend this single item as a good screening item. It may also be helpful to have an item related to the duration of sleep problems. For example, “How long have your child sleep problems been going on?” ___ Months.
Interview screening questions
Frequently, clinicians need to conduct brief screening for sleep issues, rather than using a full interview. We were unable to identify specific screening questions for infants or toddlers. We propose the following as means of capturing the issues that impact sleep in children of this age. These questions address the factors that have substantial evidence supporting their relationship to sleep issues among infants and toddlers.
| SNOOSIE | Infants (0–2 Years) |
|---|---|
| S leep hygiene |
|
| N ight-waking |
|
| O nly back on bed | Is child placed on back in crib or bed? |
| O nly breastfeeding or bottle feeding 15 minutes before bed |
|
| S leep duration | Is child getting enough sleep, including naps? |
| I ndependent settling to sleep |
|
| E nvironment |
|
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