Variation near MTNR1A associates with early development and interacts with seasons.

Melatonin is a circadian regulatory hormone with neuroprotective properties. We have previously demonstrated the association of the genetic variant rs12506228 near the melatonin receptor 1A gene (MTNR1A) with intolerance to shift-work. Furthermore, this variant has been connected to Alzheimer's disease. Because of the previously suggested role of melatonin signalling in foetal neurocognitive and sleep development, we studied here the association of rs12506228 with early development. The study sample comprised 8-month-old infants from the Finnish CHILD-SLEEP birth cohort (n = 1,301). Parental questionnaires assessed socioemotional, communication and motor development, as well as sleep length and night awakenings. The A allele of rs12506228 showed an association with slower socioemotional (p = .025) and communication (p = .0098) development, but no direct association with sleep. However, the association of the Finnish seasons with infant sleep length interacted with rs12506228. Taken together, rs12506228 near MTNR1A, which has been previously linked to adult and elderly traits, is shown here to associate with slower early cognitive development. In addition, these results suggest that the darker seasons associate with longer infant sleep time, but only in the absence of the rs12506228 AA genotype. Because the risk allele has been connected to fewer brain MT1 melatonin receptors, these associations may reflect the influence of decreased melatonin signalling in early development.

Maternal and paternal sleep during pregnancy in the Child-sleep birth cohort.

STUDY OBJECTIVES: Maternal and paternal sleep insufficiency during pregnancy appears to be a risk factor for health and wellbeing in young families. Here, we evaluated the prevalence of sleep insufficiency and symptoms of insomnia during pregnancy (at 32nd pregnancy week) and their relationship to depression, anxiety and environmental stress. METHODS: The study is based on a population based sample from Finland consisting of 1667 mothers and 1498 fathers from the Child-sleep birth cohort. We evaluated both the core symptoms of insomnia (sleep onset problems, nocturnal awakenings, too-early awakenings, and poor sleep quality) and the presence of insufficient sleep. Insufficient sleep was defined as a two-hour difference between self-assessed sleep need and reported sleep duration, or sleep duration shorter than six hours per night. RESULTS: We found that symptoms of insomnia were more prevalent among women than among men (9.8% vs. 6.2%), whereas sleep debt was less prevalent among women than among men (4.5% vs. 9.6%). Overall, 11.8% of the women and 14.9% of the men reported either significant insomnia or short sleep. Symptoms of insomnia were related to symptoms of depression both among women and men (AOR 3.8, 95% CI 2.6-5.6 vs. AOR 1.9, 95% CI 1.1-3.2), while short sleep was related to depression among women (AOR 3.3, 95% CI 1.8-5.8), and to low education, poor health and a larger number of children among men. CONCLUSIONS: The study showed that insomnia and sleep insufficiency are prevalent among women and men during pregnancy. The findings underline the impact of insomnia to both maternal and paternal health during pregnancy as well as to the implementation of effective interventions to prevent negative consequences of sleep disturbances.