The ontogeny of mammalian sleep: a response to Frank and Heller (2003)

Abstract

SUMMAR Y In a recent review, Frank and Heller (2003) provided support for their Ôpresleep theoryÕ of sleep development. According to this theory, rapid eye movement (REM) and non-rapid eye movement (Non-REM) sleep in rats emerge from a common ÔdissociatedÕ state only when the neocortical EEG differentiates at 12 days of age (P12). Among the assumptions and inferences associated with this theory is that sleep before EEG differentiation is only Ôsleep-likeÕ and can only be characterized using behavioral measures; that the neural mechanisms governing presleep are distinct from those governing REM and Non-REM sleep; and that the presleep theory is the only theory that can account for developmental periods when REM and Non-REM sleep components appear to overlap. Evidence from our laboratory and others, however, refutes or casts doubt on these and other assertions. For example, infant sleep in rats is not Ôsleep-likeÕ in that it satisfies nearly every criterion used to characterize sleep across species. In addition, beginning as early as P2 in rats, myoclonic twitching occurs only against a background of muscle atonia, indicating that infant sleep is not dissociated and that electrographic measures are available for sleep characterization. Finally, improved techniques are leading to new insights concerning the neural substrates of sleep during early infancy. Thus, while many important developmental questions remain, the presleep theory, at least in its present form, does not accurately reflect the phenomenology of infant sleep.k e y w o r d s active sleep, atonia, myoclonic twitching, rat, rem sleep, slow-wave sleep

Is Sleep Beyond Our Control?

“…Large groups of animals do not exhibit the differentiated EEG signals that are a prerequisite of an EEG based definition of sleep [10,11]. Unihemispheric sleep in the cetacean and avian phyla reveals that sleep can be achieved, in neural terms, locally [40].…”

“…The desire to study sleep at molecular and genetic levels, however, has made it necessary to define and measure sleep in genetically tractable organisms, most of which do not exhibit the defining electrographic signs of sleep. This, at least in part, has resulted in a return to behaviorally based definitions of sleep [8][9][10]. The hallmark behavioral criteria for sleep include:…”

“…(For discussion on whether electrographic and behaviorally defined sleep represent the same phenomena, please see: [10,19]). The first two behavioral criteria are the most frequently used criteria to measure sleep in the laboratory.…”

Developmental Implications of Sleep

“…Active sleep, which resembles of that REM-sleep is characterized by more tense muscle tone, eyelid fluttering, irregular breathing, and rhythmic startles. Quiet sleep, which resembles of that non-REM sleep is characterized by regular breathing, not eyelid fluttering, and little movement (Blumberg, Karlsson, Seelke, & Mohns, 2005).…”

Theory of Mind: Towards an Evolutionary Theory

“…After this, a stable sleep-wake cycle is established and the well-known sleep stages appear. For a more detailed discussion of infant sleep see Frank and Heller (2003) and Blumberg et al (2005). 20 The idea that waking consciousness may phylogenetically and ontogenetically grow out of REM sleep is not taken out of thin air.…”