Sleep, like waking, is a complex phenomenon comprising fluctuations in many neural and physiological systems. When we fall asleep, our skeletal muscle loses tone, the electrical activity in our cerebral cortex (i.e., the EEG) changes, and, during active sleep, our eyes dart around and our limbs twitch. The challenge of studying infant sleep is that these various components, which have been studied extensively in adults, do not always present themselves clearly in infants. For example, the EEG of infant rats before eleven days of age does not exhibit the clearly differentiable activity upon which researchers rely so heaviliy when judging adult sleep. These and other factors mean that we must assess infant sleep on its own terms rather than judge it against an adult standard. This is a central tenet of infant research, and one that we forget at our peril.

At that point, we had a foundation upon which we could begin examining the neural bases of sleep and wakefulness early in the infant rat's postnatal life. We have now explored medullary, mesopontine, and forebrain mechanisms involved in the modulation of sleep and wakefulness. In addition, we have documented seminal developmental changes in the statistical organization of sleep bouts in rats and knockout mice. Currently, we are also documenting the development of circadian rhythmicity in rats. Other current areas of research involve assessment of neocortical and hippocampal neurophysiological activity across development and the effect of cortical damage on phasic sleep activity.

One of the goals of our research is to identify the role that sleep plays in the development of the nervous system. We view sleep as essential to the process by which sensory and motor systems establish the precise maps that make normal function possible. This process is particularly critical during early development but also continues throughout life. We believe that sleep, especially active sleep, is critical to this process because it provides a period of relative quiescence when discrete signals can be sent and received by the nervous system.

Although our research focuses on basic research questions, it has implications for our understanding of sleep (e.g., narcolepsy) and other neurological (e.g., pediatric epilepsy) disorders. For example, using knockout mice that are not able to produce the neurotransmitter orexin--these mice, as adults, are narcoleptic--we are finding that the onset of the narcoleptic phenotype after birth entails the retention of juvenile sleep-wake characteristics, rather than the onset of a unique set of pathological features. We have also discovered that the infant rat hippocampus exhibits a suite of transient electrophysiological properties that coincide with a period of heightened susceptibility to seizures. This finding may help to provide a marker with which we can identify infants at risk for epileptic seizures.

Our research is funded by grants from the National Institute of Mental Health.

To read more about our research, you can download papers here.