life physical activity reverses metabolic and Foxo1 epigenetic misregulation induced by gestational sleep disturbance. Am J Physiol Regul Integr Comp Physiol 308: R419 -R430, 2015. First published January 7, 2015 doi:10.1152/ajpregu.00426.2014.-Sleep disorders are highly prevalent during late pregnancy and can impose adverse effects, such as preeclampsia and diabetes. However, the consequences of sleep fragmentation (SF) on offspring metabolism and epigenomic signatures are unclear. We report that physical activity during early life, but not later, reversed the increased body weight, altered glucose and lipid homeostasis, and increased visceral adipose tissue in offspring of mice subjected to gestational SF (SFo). The reversibility of this phenotype may reflect epigenetic mechanisms induced by SF during gestation. Accordingly, we found that the metabolic master switch Foxo1 was epigenetically misregulated in SFo livers in a temporally regulated fashion. Temporal Foxo1 analysis and its gluconeogenetic targets revealed that the epigenetic abnormalities of Foxo1 precede the metabolic syndrome phenotype. Importantly, regular physical activity early, but not later in life, reversed Foxo1 epigenetic misregulation and altered the metabolic phenotype in gestationally SF-exposed offspring. Thus, we have identified a restricted postnatal period during which lifestyle interventions may reverse the Foxo1 epigenetically mediated risk for metabolic dysfunction later in the life, as induced by gestational sleep disorders. epigenetics; Foxo1 gene; offspring metabolism effect; pregnancy sleep disruption; reverse epigenetic effects; physical activity THE TERM "EPIGENETICS" REFERS to DNA and histone modifications and noncoding RNA, which result in heritable changes in gene expression among the next generation without a change in the DNA sequence (5,17,29). The environment, such as diet and early life experiences, can influence the epigenome. Epigenetic abnormalities have been found to be causative factors in cancer, as well as contributing factors in autoimmune diseases, metabolic pathways, and aging. Disruption of the balance of epigenetic networks can lead to inappropriately heightened expression or silencing of genes, resulting in "epigenetic diseases". In contrast to genetic events, the potential reversibility of epigenetic states offers exciting opportunities for new therapeutic targets (9, 19).Sleep disorders are highly prevalent among pregnant women in late gestation and are characterized by increased awakenings during the night and sleep maintenance insomnia, which are potentially fraught with adverse pregnancy outcomes (13,21,38,45). Among the disorders that impose additional disruption of sleep integrity during pregnancy, sleep-disordered breathing is particularly prevalent and has emerged as a contributor to gestational diabetes mellitus, preeclampsia, as well as adverse perinatal outcomes (28, 42). However, the impact of poor sleep quality and continuity during pregnancy could transcend the gestational period and adve...