Sleep is often mistakenly conceived as a passive state; however, it actually plays a
fundamental role in regulating daytime cognitive functions such as memory and emotion
(Klinzing et al., 2019). Additionally, other phenomena suggest that complex cognitive
processing may be active during sleep. For example, lucid dreaming, the ability to be
aware of dreaming while in the dream, involves a form of volitional control during sleep
(Baird et al., 2019). Another scarcely studied experience related to regained cognitive
activity during sleep is self-awakening. People habitually use alarms to wake up at a
specific time in the morning. Interestingly, some individuals report the ability to wake
up without the aid of any timekeeper; we refer to this phenomenon as self-awakening.
Although the experience is commonly reported, certain specifics are needed to identify
and understand the phenomenon.
Firstly, awakening from sleep can be induced by external stimuli but may also occur
spontaneously. Secondly, spontaneous awakening can be divided into natural awakening,
caused by a "natural" cessation of sleep due to the dissipation of physiological sleep
pressure, or self-awakening, driven by the intent to wake up. Thirdly, self-awakening
itself requires clarification: it may be habitual (i.e., a person wakes up at the same
time every day), in which case circadian rhythms are the driving factor, or it can be
induced by will. This latter phenomenon is the primary focus of interest here.
Studying self-awakening is not only fascinating but could also provide insights into the
presence of specific cognitive processes even at minimal or absent levels of
consciousness. There are at least three cognitive operations that a sleeping person must
successfully perform to awaken at the intended time. First, they must encode and remember
the target time, which should be easily accessible; second, elapsed time during sleep
should be constantly estimated and compared to the target time; third, one must regain
voluntary control during sleep to awaken. All these operations must be carried out while
the sleeping subject is in a state typically characterized by minimal levels of
consciousness (Tononi & Massimini, 2008).
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.