Longitudinal changes in sleep patterns and circadian rhythm metrics in preschool-age children from Northern Mexico.

Abstract Objectives To assess changes in sleep parameters and circadian rhythm metrics measured by actigraphy in preschool-aged children. Design Longitudinal analysis over 1 year. Participants Ninety-four children living in Tijuana and Ensenada, Mexico. Measurements Children wore accelerometers on the right hip for one continuous week at baseline and 1-year follow-up. Parents recorded child bedtime, waketime, and naps in sleep diaries. We used cosinor and nonparametric approaches to calculate circadian rhythm metrics. Results At baseline, children had a mean age of 4.2 years, and 51.1% were girls. In multivariable models adjusted for age, gender, BMI category, parental education, household income and city, at follow-up children had significantly earlier waketimes (β = -7.99 minutes, p Conclusions Mean increases in nighttime sleep and earlier wake times over one year were concomitant with decreases in overall activity levels and increases in circadian rhythm robustness. Co-sleeping was a predictor of sleep disturbances. This study provides longitudinal evidence regarding changes in sleep and circadian metrics in a sample of children from an under-researched sociodemographic group during an important, early life period.