Sleep duration in 2 year olds proportional to Vitamin D levels

The Association Between 25-hydroxyvitamin D Levels and Children's Sleep-Wake Patterns: A Prospective Cohort Study

Sleep Med, 67, 207-214 2019 Dec 12 PMID: 31952028 DOI: 10.1016/j.sleep.2019.11.1252

Yujiao Deng 1, Guanghai Wang 1, Xiuxia Ye 2, Yanrui Jiang 1, Qingmin Lin 1, Shumei Dong 1, Yuanjin Song 1, Lixia Zhu 1, Min Meng 1, Wen Li 1, Qi Zhu 1, Wanqi Sun 3, Fan Jiang 4

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Objective: To explore the association between vitamin D in cord blood or in venous blood and children's sleep-wake patterns at two years of age.

Methods: Data were from 209 children in a birth cohort, Shanghai Sleep Birth Cohort Study (SSBC). 25-Hydroxyvitamin D (25(OH)D) was assessed in cord blood and venous blood samples at two years of age by electrochemiluminescence immunoassay. Children's sleep-wake patterns were measured with the Brief Infant Sleep Questionnaire (BISQ) and Acti-Watch at two years of age.

Results: The prevalence of vitamin D deficiency (defined as <50 nmol/L) was 50.4% in cord blood and 28% at two years of age. The cord blood 25(OH)D level was not significantly associated with children's sleep at two years of age. Children with 25(OH)D deficiency at two years old had shorter reported and actigraphic night sleep duration (NSD) and total sleep duration (TSD) than those with normal 25(OH)D concentration. 25(OH)D level at two years old was positively associated with night and total sleep duration (βreported-NSD = 0.6, p = 0.011; βreported-TSD = 0.6, p = 0.029; βactigraphic-NSD = 0.82, p = 0.003; βactigraphic-TSD = 0.78, p = 0.006), but was not associated with daytime sleep duration. There was no significant association between 25(OH)D level with night waking duration and midpoint of sleep either measured subjectively or objectively.

Conclusion: We found that not cord blood 25(OH)D level but two-year-old 25(OH)D level was associated with children's sleep-wake patterns at two years of age. These findings suggest more attention should be paid to the assessment of 25(OH)D levels in children with short sleep duration.