Sleep Disturbances and Mental Well-Being of Preschool Children during the COVID-19 Pandemic in Mexico

**Background:** The COVID-19 pandemic and its associated confinement measures disrupted children's routines worldwide, raising concerns about sleep and mental health. In Mexico, confinement lasted at least one continuous year. While prior studies reported mixed data on preschoolers' sleep during the pandemic, most relied on subjective parental reports rather than objective measures. This study aimed to comprehensively assess sleep parameters—using both subjective questionnaires and objective wrist actigraphy—and mental well-being in Mexican preschool children after prolonged confinement.

**Methods:** This cross-sectional study was conducted from September to December 2021. Parents were recruited through two active WhatsApp school groups. Inclusion criteria for parents: ≥18 years, living in Mexico during the pandemic, primary caregiver of a child aged 3–6 years. Children were eligible if aged 3–6, living in Mexico during the pandemic, not taking sleep-aid medication, and not hospitalized or having had an infectious disease in the prior 12 weeks. The final sample comprised 51 parent–child dyads. Parents completed a sociodemographic and confinement questionnaire, the Children's Sleep Habits Questionnaire (CSHQ; cutoff >41 indicates sleep disorder, >52 indicates severe disturbance), and the Strengths and Difficulties Questionnaire (SDQ). Children wore a GENEActiv Original wrist actigraphy device for seven consecutive days; parents also kept a sleep diary. Actigraphy data were processed using GENEActiv R Markdown Analysis Tools, with LOESS regression to detect nocturnal awakenings. Groups were compared using Fisher's exact test, χ², t-tests, or Mann–Whitney U tests. Cox regression evaluated hazard risk for sleep time reduction.

**Key Results:** The mean age of children was 5.27 years; 56.8% were female; 62% had partially returned to school. Parents reported that 72% of children had increased electronic device use, with tablets being the most common. The prevalence of sleep disturbances (CSHQ > 41) was 68.6%, with 23.53% classified as severe (CSHQ > 52). Bedtime resistance and daytime sleepiness showed the largest differences between severity groups (p < 0.01). Parental sleep diaries reported an average total sleep time of 9.8 hours, whereas actigraphy recorded only 7 hours. Both values are below the American Academy of Sleep Medicine recommendation of 10–13 hours. Total sleep time and sleep efficiency from diaries were significantly associated with the CSHQ > 41 group (p = 0.03 and p = 0.04, respectively). Preterm birth was associated with higher sleep disturbance severity (p = 0.04; OR 6; 95% CI 1.12–32.24). Allowing tablet use in the bedroom near bedtime was significantly associated with sleep disturbances (p = 0.01; OR = 6.67; 95% CI 1.62–27.38). Cox regression confirmed that tablet use near bedtime significantly influenced total sleep time and motionless sleep time reduction (p = 0.01). On the SDQ, 15.6% of children scored above 14 (indicating mental health concerns), with hyperactivity scoring highest, followed by behavioral difficulties and emotional distress. Higher sleep disturbance scores were significantly associated with SDQ total score (p < 0.01), externalizing (p = 0.01), internalizing (p < 0.01), emotional distress (p < 0.01), and behavioral difficulties (p < 0.01).

**Clinical Implications:** Sleep disturbances were highly prevalent (68.6%) in Mexican preschoolers after one year of COVID-19 confinement, exceeding rates reported in some other countries. The marked discrepancy between subjective (9.8 h) and objective (7 h) sleep duration underscores the importance of using both measures in clinical assessment. Tablet use in the bedroom near bedtime emerged as a strong, modifiable risk factor for sleep disturbances and reduced motionless sleep, which may impact deep sleep and associated neurophysiological processes. The association between sleep disturbances and mental health symptoms (emotional distress, behavioral difficulties) suggests bidirectional influences that warrant integrated screening and intervention. Children born preterm may represent a particularly vulnerable subgroup. Clinicians should counsel families on removing electronic tablets from bedrooms and limiting evening screen exposure, and consider actigraphy when objective sleep data are needed. Age-tailored interventions addressing both sleep hygiene and emotional regulation are recommended for this population.