Table 1.

Summary of the included studies on sleep in healthy children.

S no.	Author, country	Time of the study	Participants	Scales for sleep	Study design	Comparator	Prevalance of sleep disturbance	Sleep quality	Sleep duration	Other results
Pre-schoolers
1.	Liu et al. [8], China	February 17–19, 2020 (Home confinement measures in place)	1619 caregivers of presechooler, aged 4–6 years)	Children's Sleep Habit Questionnaire (CSHQ)	Cross sectional, online survey (WeChat)	Sociodemographically similar sample of preschoolers in 2018	CSHQ score>41: 900/1619 (55.6%)in COVID-19 sample and 339/436 (77.7%) in 2018 sample	CSHQ total and subscale scores were all significantly lower in the COVID-19 sample	During COVID-19 outbreak, there was •Delayed bedtime and waketime; •Increased nocturnal sleep duration •Comparable 24 h sleep duration	•Behavioural practices (sleeping arrangement, reduced electronic device use, diet) and parenting practices (harmonious family atmosphere and increased communication) were associated with less sleep disturbances
2.	Giorgio et al. [9], Italy	April 1st- 9th, 2020; national lockdown in Italy	245 mothers of preschool children aged 2–5 years	Sleep Disturbance Scale for Children (SDSC, Italian version provided by Bruni)	Cross sectional, Online survey	Retrospective account before the lockdown (in February, 2020)	SDSC score > 39 in 110/245 (44.7%) during the lockdown and 102/245 (41.5%) before lockdown	Total SDSC score did not signifcantly change during lockdown	During COVID-19 outbreak •Delayed bedtime and waketime	•Mother's sleep patterns directly affect child's sleep patterns. •Poor inhibitory self-control, poor control of emotions by mother and poor strengths and difficulties questionnaire scores of mothers resulted in poor sleep quality in children.
3.	Zreik G et al. [10], Israel	April 20–30, 2020; after 4 weeks of lockdown in Israel	Mothers of 264 children aged 6–72 months	Brief Infant/Child Sleep Questionnaire Based on child's sleep during the last 2 weeks of home confinement	Cross-sectional, web based survey	none	Not mentioned	Negative change in 76/264 (29%), improved 32/264 (12%), no change in 59%	Decreased in 92/264 (35%), increase in 66/264 (25%), no change in 40%	•Maternal COVID-19 anxiety correlated positively with child's sleep latency and negatively with child's sleep duration •Improvement in child's sleep quality and duration was associated with decreased insomnia symptoms in mother
4.	Carroll N et al. [11], Canada	20 April 2020 to 15 May 2020	Parents of 310 children aged 18 months to 5 years	Sleep duration parameter Pittsburgh Sleep Quality Index Qualitative sleep assessment: self-made questionnaire	Longitudinal family-based cohort, online survey	–			Remained same in (211/310) 68%; Increased in 53/310 (17%)
5.	Dellagiulia A et al. [12]; Italy	Feb 25- March 25; Lockdown in place	37 mothers of preschool children aged 3–6 years	Questionnaire investigating trajectory of sleep duration, sleep quality and bed-time routine administered twice a day for 30 days	Longitudinal study	–		Piecewise growth curve with a linear and decreasing pattern from first day of study till March 11with subsequent stablization	Quadratic pattern with decrease and then stabilization of this pattern of decrease
Children and adolescents
1.	Guerrero et al. [13], Canada	April 2020, containment measures in place	A national sample of 1472 Canadian parents of children (5–11 y; N = 693) and youth (12–17 years; N = 779)	A 1-item measure taken from the Canadian Health Measures Survey. Duration of sleep/24 h in last 1 week was enquired.	Cross sectional, online survey	–	Not mentioned	Not mentioned	426/1472 (28.9%) did not meet sleep duration recommendation	The adherence group included those with household annual income ≥100,000 CAD and whose parents reported a slight increase in their child's sleep duration since COVID-19
2.	Moore et al. [14], Canada	April 2020, containment measures in place	Same as study by Guerrero et al.	Same as study by Guerrero et al.	Cross sectional, online survey				208/690(30.1%) children aged 5-13y and 216/774 (27.9%) youth (14-17y) did not meet sleep duration recommendations had longer sleeping hours than boys	Improvement in sleep time and quality was associated with •Being younger parent, •Participation of parents in physical activity, •Parents discouraging screen time, •Parents encouraging children to sleep
3.	Mitra R et al. [15], Canada	April 2020, containment measures in place	Same as study by Guerrero et al.	Same as study by Guerrero et al.	Cross sectional, online survey			Decrease in 209/1472(14%); Increase in 251/1472(17%). However the quantum of change or in abnormal range not specified	Increased in 609/1472 (41.4%); Decreased in 101/1472 (6.9%)	Children with decreased outdoor activities had increased sleeping time and decrease in sleep quality.
4.	Medrano M et al. [16]; Spain	At end of March 2020, COVID-19 confinement measures in place	Children aged 8–16 years (55 girls) enrolled in MUGI project who agreed to participate (N = 113)	Sleep time was calculated on the basis of wake-up time and bedtime from the daily log of each child	Longitudnal online survey with two time points	Timepoint before confinement September–December 2019 (N = 291)			Not meeting sleep recommendation (<8 or >9 h/d):96/108 (88.9%) during weekdays and 102/108 (94.4%) during weekends; sleep duration increased on both during weekdays and weekend
5.	Baptista AS et al. [17], Brazil and Portugal	April 24–26, 2020; social distancing measures in place	Parents/caregivers of 3- to 15-year-old children (N = 253); 50.2% from Brazil	Sleep Disturbances Scale for Children	Cross-sectional online questionnaire	–		Change in sleep quality was assessed. Poorer sleep quality in 108/253 (42.7%)		Sleep breathing disorders, sleep-wake transition disorders, and disorders of excessive somnolence were associated with poor oral hygiene
6.	Zhou SJ et al. [18], China	March 8th – 15th, 2020; Lockdown in place	11,835 adolescents and young adults aged 12–29 years from 21 provinces; Self- rated, School going adolescents: 7736	Pittsburgh Sleep Quality Index (PSQI) for sleep quality during the previous month based on 7 components.	Cross-sectional, Online survey, Wenjuanxing platform	–	Sleep disturbance: 4283/7736 (55.4%), insomnia:1693 (21.9%), those using sleep medication: 84/7736 (1.1%);	Bad or poor sleep quality: 818/7736 (10.6%) Sleep efficiency< 85%: 1528/7736 (19.8%); sleep latency > 30 min: 711/7736 (9.19%); daytime dysfunction:4065/7736 (52.6%)	No more than 7 h: 2896/7736 (37.4%); More than 9 h: 765/7736 (9.9%)	•Junior school students slept better. •Risk factors for insomnia symptoms in adolescents and young adults include female gender, depression, and anxiety.
7.	Zhou J et al. [19], China	Feb 20–27, 2020 (Home confinement measures in place)	4805 female adolescents; 11–18) years; self	Sleep duration per day	Cross sectional online survey (WeChat)				<6 h: 218 (4.5%) 6–8 h: 2854 (59.45%) >8 h/day: 1733 (36.1%)	Sleep was assessed as a part of depression correlates. Adolescents with sleep duration<6 h had significantly higher odds of suffering from depression on univariate and multivariate logistical regression analyses
8.	AMHSI Research team [20]; USA and Israel	March 1 to June 15, 2020; stay at home period of ≥1 month	1142 adolescents aged 15–18 y.	Daily logs, the sleep-wake patterns questionnaire, phone/Zoom interviews	Longtudinal online survey				Evening bedtime unchanged: 18.6%; was later (“owls”) in 66.1%. Morning getup time unchanged in12.6% and became late (“owls”) in 83.3%	•Most significant changes in sleep timing occurred during the first week of stay-at-home •The largest group of participants (35%) moved their bedtime to “about 1 h later”.
9.	Lopez- Bueno et al. [21]; Spain	March 22-May 10, 2020; national confinement in place	516 parents of 860 children and adolescents aged 3–16 years	Sleep time/day	Cross sectional; online web-form	Before the confinement (retrospective questioning)			Sleep time tended to slightly increase during the confinement. The subgroup of younger children had more sleep hours compared with older ones.