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Short sleep duration increases the severity of obesity and is related to cardiovascular risk factors in children.

Purpose The aim of this study was to investigate screen media use and sleep patterns among Spanish adolescents during the lockdown (LD) of the first peak of the coronavirus pandemic. Methods Cross-sectional community-based study of adolescents aged 11–18 years. An online questionnaire with queries about screen time, sleep, and other healthy habits was completed by parents or guardians. Results Overall 265 adolescents were enrolled. The mean age was 13.6 ± 2.3 years, 58% were boys, 68% were in secondary school and 72% lived in urban areas. Before the LD (BLD) 87% of adolescents used electronic devices < 4 h/d, while during the LD (DLD) screen time was > 4 h/d in 75% of cases ( p < 0.0001). A delayed wake time and bedtime weekdays (BLD wake time weekdays: later than 09:45 0.0% vs. DLD 30%, p < 0.0001, and BLD bedtime weekdays: later than 00:30 3% vs. DLD 35%, p < 0.0001) and weekends DLD was observed. Adolescents who used electronic devices > 4 h/d DLD compared with those who used < 4 h/d reported more frequently long sleep latency (93% vs. 7%, p = 0.007), low sunlight exposure (77% vs. 23%, p = 0.031), less physical activity (86%. vs. 15%, p = 0.011) and weight gain (78%. vs. 22%, p = 0.049). Conclusions During the lockdown Spanish adolescents reported elevated screen time and delayed sleep patterns. An increase in screen media use was associated with unhealthy habits.

Objective: Cesarean section rates are increasing in developed countries and could be performed as an emergency or elective procedure. Our research aim was to determine whether elective cesarean section influences the melatonin content, the main circadian hormone, in human milk. Methods: Twenty-one women after vaginal delivery and 18 women after elective cesarean section were included. Only healthy mothers with normal newborns exclusively breastfed were recruited. Two samples of human milk were collected for each woman at three stages of lactation: colostrum, transitional milk, and mature milk; at each stage, one daytime sample and another nighttime sample were obtained. In total, 228 milk samples were studied. The melatonin content was analyzed by enzyme-linked immunosorbent assay. Results: Melatonin rhythmicity with higher melatonin content at night was maintained at each of the three stages of lactation, regardless of the type of delivery. A higher melatonin content was found in daytime colostrum after cesarean section with respect to colostrum obtained from mothers after vaginal delivery (30.3 pg/mL versus 14.7 pg/mL, p = 0.020). Melatonin content decreased progressively throughout the course of lactation in both groups. This decrease was significant when comparing transitional milk to colostrum in the cesarean group, both in the daytime (p = 0.016) and nighttime samples (p = 0.048). Conclusions: Cesarean section is associated with an increase in daytime colostrum melatonin. No difference was observed in mature milk with respect to vaginal delivery. Melatonin values in human milk decrease during the first month of lactation and circadian rhythmicity was observed irrespective of the mode of delivery.