To the best of our knowledge, this is the first age specific comparative study on infant and toddler sleep patterns before the COVID-19 pandemic and during confinement due to COVID-19 pandemic.
Adequate sleep patterns in infants and toddlers are relevant as they are linked to proper and long-term social-emotional development. A previous study found that later bedtimes and less total sleep across the 24-hour period predicted higher internalizing problem scores (including indices of depression/withdrawal, general anxiety, separation distress, and inhibition) (12). Regarding sleep patterns in pediatrics specifically during the COVID-19 pandemic, recent literature has found that changes in sleep patterns are diverse and no unified change for the worse can actually be expected.
Total sleep time is a relevant variable in describing children sleep patterns. In our study, we found a decreasing trend in total sleep time for all age groups during confinement however statistically significant differences were only found in the youngest infant group (three-six months) with a median duration of total sleep time before confinement of 13 hours (IQR 11.5–14.5) vs. median of 12 hours during confinement (IQR 11.1–13.2) as well as in the oldest toddler group (25–36 months) with a median duration of total sleep time before confinement of 11.5 hours (IQR 10.7–12.0) vs. 11.0 hours (IQR 10–12). Similarly, in a recent study analysing sleep patterns in Spanish children of relatively comparable age (0–2 years of age) during home confinement, total sleep time reported was mean of 10.98 hours; (SD = 1.8) (13), Another research based in Spain on sleep patterns during COVID-19 pandemic analyzing 280 children from 0–4 years of age, described a mean sleep time in infants younger than one year of 11.69 hours (SD = 1.87) and among 1–2 years 11.35 hours (SD = 1.74) (14). Lecuelle (15) found in French preeschoolers that during home confinement, the length of nocturnal sleep increased from 10.3 to 10.9 hours however with no impact on the total duration of sleep over 24 hours.
Regarding adequacy of sleep duration in our sample, and based on the WHO guidelines for children younger than five years as reference (16) (infants younger than one year of age should sleep a minimum of 12 hours of total sleep time and from 1 to 2 years of age a minimum of 11 hours), remarkably in our research a quarter of them did not reach this total sleep time of 12 hours (IQR 11-12.7).
Difficulties initiating and maintaining sleep increased in our study, finding that infants and toddlers during confinement went to bed slightly later. This fact was especially substantial in both the youngest infants and the oldest toddlers. We also found longer sleep onset latencies (> 30 minutes) during COVID-19 confinement, with infants and toddlers showing more difficulty to fall asleep. Interestingly, however, prolonged nocturnal awakening of more than 1 hour decreased. Previous literature has already described similar findings regarding infants and toddlers with delayed bedtime being significantly associated with bedtime resistance even when adjusting for total sleep time (13, 17).
A study examining 3157 preschoolers in Chile found that during early stages of the pandemic, sleep duration increased, and sleep quality declined. Toddlers and preschoolers with space to play at home and living in rural areas experienced an attenuated impact of the pandemic restrictions on their physical activity levels, screen time, and sleep quality (18). Therefore, home confinement might play a role in regulating sleep patterns intertwined with other variables previously described such as sleep light, activity level, social contact, psychological well-being among others (7, 14, 19). Previous literature has also pointed out that low optimism and parental stress correlates negatively with sleep duration and parental perception of sleep quality (20) as well as the potential influence of longer screen time exposure in explaining later bedtimes (14, 19).
The original BISQ Questionnaire (10) described very concrete sleep patterns that might indicate the need for a child to be further screened for sleep difficulties (total sleep time less than nine hours, more than three night awakenings and duration of awakenings longer than one hour). When comparing infants and toddlers presenting with one or more of these criteria in both samples we found a statistically significantly increase of infants and toddlers presenting with one of this sleep criteria during COVID confinement (37% of infants and toddlers vs. 25% before COVID-19 confinement) (p < 0.001).
Regarding parental perception of sleep difficulties, 44% of parents evaluated during COVID-19 confinement indicated their child had a sleep problem whereas 39% of parents stated sleep difficulties before COVID-19 confinement. Zreik (21) analyzed in Israel the possible negative implications for sleep during COVID-19 pandemic both for mothers and infants and toddlers 6–72 months of age, finding that about 30% of mothers reported a negative change in child's sleep quality and a decrease in sleep duration. However there were also mothers who reported a positive change in sleep quality during COVID-19 pandemic (21).
There were some limitations to the present study. Home confinement in Spain took place between March-May 2021, however we recruited our sample from April-June 2021 after receiving approval from our Ethics Committee, therefore a memory bias in this short time span might be taken into account. Both samples (before confinement and during confinement ) showed slight differences in some characteristics such as a slightly uneven proportion of toddlers among 19–24 months of age in both samples (21% before confinement vs.14% during confinement (p = 0.026)), a higher proportion of parents with a university degree (64% before confinement vs. 77% during confinement (p < 0.001)) and a higher percentage of parents younger than 25 years of age (1.5% before confinement vs. 10% during confinement (p < 0.001)). This might be probably due to the relatively smaller sample recruited during confinement. However, methodologically in both groups we followed same procedural guidance.
Our sample may have a limited generalizability as participants were recruited by convenience sampling and were mostly living in the region of Catalonia in Spain. Regarding demographical characteristics, sample size limitations have to be noted. Despite this limitation, the results in this current research showed statistical significance. Our sample included an unbalanced proportion of families with higher education, as can be expected from a primarily internet-based study. Nevertheless, our findings were consistent with previous cross-cultural web-based studies (10, 22, 23), showing similar epidemiological characteristics so we believe we have obtained similar segments of the population within our country for purposes of cross-cultural comparison (10, 23). For the present research we based the definition of sleep difficulties solely on the criteria presented in the BISQ (10) thus not taking into account other aspects of this complex construct. We used a limited number of sleep variables to define sleep ecology without taking into account further variables that have shown to have a predictor value for sleep quality such as the use of routines, parental stress during COVID-19 pandemic as well as sociodemographic relevant data such as size of living unit, income, housing location and space, remote-working of one or both parents among others.
The reliance on parental reports in assessing infant sleep has inherent limitations; however previous research (24, 25) has shown a high correlation between parent-reported sleep duration and actigraphy-recorded sleep duration in young healthy children. Further, parents with concern about their child’s sleep may have been more likely to participate, skewing this aspect of our results. Information bias may be an inherent limitation to web-based surveys. However, the fact that there was not an interviewer carrying out the questionnaire may have decreased an unacceptability bias (26).