Cognitive Control During Sleep: the Strange Case of Self-Awakening

The experimental model of self-awakening highlights several important issues, particularly the lack of a reliable model for estimating the time interval, from minutes to hours, that passes between falling asleep at night and the moment of self-awakening. This may be explained by limited knowledge of ultradian brain oscillators (i.e., biorhythms with periods shorter than 24 hours) related to the perception of time during nighttime sleep, although the processes involved in the internal timing of circadian rhythms have been extensively studied. These are biologically regulated by a relatively small group of around 10,000 neurons in the suprachiasmatic nucleus of the hypothalamus, oscillating with a 24-hour rhythm. Little is known about ultradian timekeepers of sleep, especially related to the REM (Rapid Eye Movement) sleep cycle, but they likely play a crucial role in self-awakening. So far, self-awakening has been studied using various subjective and objective methodologies, including questionnaires, sleep diaries, actigraphy, and polysomnography. However, no study has integrated all these different approaches Objective The primary aim of this project will be to investigate the psychophysiological and neuropsychophysiological characteristics underlying the phenomenon of self-awakening, introducing an innovative multimodal approach by combining three main methodologies (ecological assessment, neuropsychological approach, and polysomnographic recording). Specifically, the first part of the study will aim to confirm, through an actigraphic survey, that subjects who report this ability at a subjective level (evaluated via the SAQ questionnaire) are indeed capable of performing it. Secondly, the polysomnographic study will aim to evaluate the EEG characteristics of 'self-awakeners' in the 30 minutes preceding self-awakening, compared to those preceding forced awakening caused by an external stimulus. Finally, the neuropsychological assessment will aim to evaluate differences in the cognitive control domains and temporal estimation abilities in 'self-awakeners' compared to subjects unable to self-awaken. The hypothesis is that subjects capable of self-awakening will exhibit distinctive neurophysiological and neuropsychological characteristics. In particular, these subjects are expected to show a reduction in the density and power of slow waves starting 30 minutes before self-awakening, thus indicating the ability to inhibit deep sleep in preparation for wakefulness. Additionally, it is hypothesized that these subjects may exhibit better performance in neuropsychological variables related to cognitive control and temporal estimation.