Sleep is a complex phenomenon that is essential to normal behavioral and biological functioning. Sleep disturbance in infants and children is of great concern to their parents, but in more general terms, patterns of sleep and circadian rhythms are often overlooked as influences on trajectories of human development. Trends over time in the United States and other developed countries show significant competition between sleep duration and timing and increasing demands and high reward activities. As with other behaviors (e.g., eating, exercise), individuals make daily decisions regarding when and how much to sleep in the context of other social activities, environmental demands, and psychophysiological drives. Such disruptions in sleep patterns subsequently influence basic sleep-wake regulation and circadian regulation, and other time- and state-linked biological processes.
Chronic and acute sleep loss and sleeping outside of the optimal circadian phase can result in persistent alterations in behavior and mechanisms regulating behavior. Investigators have established connections between disrupted circadian regulation, disordered sleep, and decreased ability to form new memories, as well as changes in metabolic regulation, inflammation, and immune response. Furthermore, mutations in genes involved in regulation of circadian rhythms have been shown to have effects on behavioral outcomes including cognition and mood (e.g., aggression). Alterations in social systems and social learning and behavior are also generated by individuals experiencing altered sleep processes.
The NICHD supports and conducts research on sleep, circadian rhythm, disruptions in these areas, and effects of those disruptions. Some of this research is described below.
Institute Activities and Advances
The Child Development and Behavior Branch (CDBB), within the Division of Extramural Research (DER) , is interested in research and research training relevant to the influence of the quantity and quality of sleep on the psychological, psychobiological, language, behavioral, and educational development of young people from childhood through young adulthood. The CDBB is also interested in the relationship between sleep and social, affective, and cognitive development; aggression and violence; and health, and it has a corresponding interest in health promotion and health-risk behaviors.
Current CDBB research examines how sleep shapes social development and studies the role of parenting in infant sleep regulation. Other studies investigate the impact of circadian tendencies on sleep deprivation in adolescence and address early interventions to improve sleep, increase physical activity, and affect regulation in young adolescents.
- Sleep Problems Can Lead to Intimate Partner Violence Over Time
On average, 24 people per minute are victims of rape, physical violence, or stalking by an intimate partner in the United States. Over the course of a year, that equals more than 12 million women and men. To better understand how to prevent violence, scientists looked at the relationship between sleep deprivation and intimate partner violence. Previous research suggested that sleep deprivation and partner violence were related. However, it has been difficult to determine whether problems in the relationship caused sleep deprivation, or whether sleep deprivation caused problems in the relationship.
Researchers assessed sleep problems and both physical and psychological abuse over the course of a year in 215 couples living together with at least one school-aged child. The results indicated that sleep problems can lead to psychological abuse over time, but not necessarily to physical abuse. Both men and women who reported sleep problems early in the year were more likely to commit increased psychological abuse later on. Although men’s sleep problems did tend to precede physical abuse, this relationship was weak and not statistically significant once other important factors (such as income) were taken into account. The results also showed that intimate partner violence, physical or psychological, did not lead to later increases in sleep problems for either men or women. The results suggest that interventions to improve sleep patterns may be a useful adjunct to other methods used to help couples at risk of intimate partner violence. PMID: 22468689
The Population Dynamics Branch (PDB), also in DER, supports research and training on sleep and circadian rhythms within its mission in demography, reproductive health, and population health. Research includes studies relating sleep and circadian rhythms to demographic events and processes within the context of the long-reaching effects of early-life influences and policy factors (e.g., shift work, school schedules) on health. A study on the effects of language-based bedtime routines found that singing, reading, and storytelling at bedtime improved nighttime sleep duration and verbal test scores. In population health, the PDB supports research on human health—including productivity, behavior, and development—using defined populations and probability samples.
The DER’s Pediatric Growth & Nutrition Branch (PGNB) also has an interest in the relationship between sleep and childhood obesity, specifically the relationship between duration and/or quality of sleep and children’s eating and physical activity behaviors, as well as energy balance and weight control.
The Intellectual and Developmental Disabilities Branch (IDDB), within DER, supports grants that address sleep disturbances or altered circadian rhythms as part of conditions associated with developmental disabilities. These disabilities may include chromosomal disorders, such as Down syndrome and other trisomies, and genetic syndromes, such as Fragile X syndrome, Rett syndrome, and Cornelia de Lange syndrome. Some genetic conditions (e.g., Smith-Magenis syndrome) are associated with specific disruptions in sleep that can inform studies of normal and abnormal sleep. In addition, many individuals with autism spectrum disorders, a seizure disorder, and/or self-injurious behaviors suffer from either sleep apnea or disrupted sleep cycles. Little is known about the nature of the sleep disorders or disruptions in circadian rhythm that occur in these conditions and the impact they have on the individuals and their family members.
The DER Maternal & Pediatric Infectious Disease Branch (MPIDB) supports research on sleep and sleep disturbances in children, adolescents, and women affected by HIV/AIDS . Researchers from the Pediatric HIV/AIDS Cohort Study found recently that HIV infection was associated with alterations in sleep duration and daytime sleep patterns, as well as neurocognitive factors.
The interests of the DER Pregnancy and Perinatology Branch (PPB) fall primarily within two areas: Sudden Infant Death Syndrome (SIDS) and sleep-disordered breathing (SDB) during pregnancy. In SIDS, efforts include research on its causes/etiology, identification of infants at risk, and development and implementation of risk reduction/preventive strategies. Supported research in SDB has indicated that there is an association between SDB and adverse pregnancy outcomes, such as preeclampsia, preterm birth, and fetal growth restriction. Furthermore, the intermittent hypoxia associated with SDB may lead to changes in the intrauterine environment that predispose offspring to metabolic and cardiovascular disorders. The Fertility & Infertility (FI) Branch in DER is currently studying sleep disorders in women with polycystic ovary syndrome and how these disorders might contribute to metabolic dysfunction.
The National Center for Medical Rehabilitation Research (NCMRR) is interested in improving our understanding of the impact of sleep quality during rehabilitation, including the development of research milestones that could lead to improved clinical practice and standards of care. There is a significant need for research that focuses on persons with physical and cognitive disorders and on individuals who develop chronic physical disabilities resulting from traumatic injury or other medical conditions, including stroke, multiple sclerosis, and cerebral palsy. Because sleep disturbances may occur in conjunction with other conditions that are secondary to the primary cause of disability, their potential effects could be difficult to define in relation to a specific medical condition and the overall functioning of the individual.
Researchers in the Section on Neuroendocrinology, within the Division of Intramural Research, investigate the pineal gland and regulation of the hormone melatonin, which is produced by the pineal gland. This research aids the study of human diseases relating to circadian rhythms, including endocrine pathologies, sleep and mood disorders, and deficiencies in alertness. Researchers in the section also pursue a better understanding of the changes in gene expression that occur in the pineal gland over a 24-hour period.
Other Activities and Advances
- The Collaborative Home Infant Monitoring Evaluation (CHIME) Study, now complete, was a multicenter cooperative study of home monitoring that sought to determine whether home monitors are effective in identifying cardiorespiratory episodes that are dangerous to the infant's health.
- The National Infant Sleep Position (NISP) Study, conducted from 1992 to 2008, was a multicenter cooperative study of infant sleep aimed at assessing infant care practices and the dissemination of recommendations for infant sleep position.
- The Work, Family, Health, & Well-Being Initiative, supported by the NICHD PDB, seeks to improve the health and well-being of people in the workplace and families by identifying factors that improve worker performance and family health. The Initiative includes the Work, Family, & Health Network , which is co-funded by the PDB and the Centers for Disease Control and Prevention to conduct interdisciplinary research on the health and well-being of workers and their families.
- The Pregnancy and Perinatology Branch partners with other organizations on the Lifestyle Interventions For Expectant Moms (LIFE-Moms) Consortium . Seven clinical trials on lifestyle interventions of overweight and obese pregnant women will collect data on sleep, including schedule, quantity, habits, disorders, and daytime sleepiness. The Consortium is funded by the NICHD and several other NIH Institutes.