For many years, researchers have conducted true experiments to determine the effects of sleep deprivation in adults. These studies have demonstrated conclusively that cognitive processing is diminished not only after total sleep deprivation (no sleep for up to several days), but also after partial sleep deprivation where typical sleep is reduced by a few hours a night. These studies are very difficult to conduct with children due to ethical concerns with depriving children of sleep. In a few studies, however, researchers have gotten parents and children to agree to restrict their sleep slightly to observe effects on performance of mental tasks. Sadeh, Gruber, and Raviv (2003) showed that restricting sleep to one hour less than usual resulted in lower performance on neuropsychological tests. A new study using similar methodology has been done by Dennis Molfese and colleagues at the University of Nebraska. The researchers had parents record the typical sleep patterns of their six-year-olds for a week and then assigned children either to an experimental group who were allowed to sleep one hour less than usual for a week, or a control group who continued to sleep their usual amounts for a week. Parents completed diaries of sleep times, and children wore actigraphs to validate their sleep times. To control for confounds, none of the children had clinical sleep disorders, ADHD, asthma, or allergies. During the study, they were asked not use caffeine, medications, or take naps.
At the end of the week, children performed a test of speech perception task where they identified the beginning sounds of syllables, a task that is predictive of later language development. During the task, electrodes on the scalp recorded electrical activity (Event Related Potentials) in specified areas of the brain known to relate to speech and language. Significant differences were found in five different brain areas between the experimental and control groups with sleep-restricted children showing slower responses.
This is the first study to demonstrate effects of mild sleep deprivation in children at the physiological level while processing speech sounds. When considered along with the few other experimental studies with children and with what we know from research with adults, the implications are very important. A reduction in sleep time of only one hour can measurably impair children’s cognitive processing. Children who attend school are required to listen to teachers’ instructions, perceive them accurately, relate them to what they already know, and remember new concepts. All of these processes must be done repeatedly within seconds or learning will be compromised.
Molfese, D.L., et al. (in press). A One-Hour Sleep Restriction Impacts Brain Processing in Young Children Across Tasks: Evidence From Brain Recordings. Developmental Neuropsychology.
Sadeh, A., Gruber, R., & Raviv, A. (2003). The effects of sleep restriction and extension on school-age children: What a difference an hour makes. Child Development, 74, 444-455.