Dreaming during the Sleep-Onset Process

This chapter provides the first full synthesis of the large amount of systematic scientific information that is available on the sleep-onset process, including what is known from studies of dreaming during the sleep-onset process. It overviews the neurophysiological substrates that are involved in triggering sleep and uses the findings from neuroimaging studies to explain how the neurocognitive networks that support consciousness gradually become less active and give way the imagination network, which remains active. It uses results from awakenings in sleep-dream laboratory studies to show that participants begin to dream as the sleep-onset process unfolds. These studies further reveal that dreaming increases as the process unfolds, and that there are individual differences in when the participants report dreaming. Also, a few participants continue to think or experience drifting waking thought but do not dreaming. These studies are theoretically important because they show that dreaming can occur outside of sleep, which in turn reinforces the general idea that dreaming occurs whenever the imagination network becomes ascendant and external stimuli are excluded.