Adriana Alcaraz-Sanchez

While most research on sleep mentation focuses on dream reports, sleep experiences can also include reports lacking content, such as white dreaming—the feeling of knowing one dreamt but being unable to recall its contents. I claim that white dreaming is a metacognitive feeling, akin to tip‐of‐the‐tongue and déjà experiences. Conceiving it this way allows for a more nuanced understanding of its nature and causes. Drawing on research on metacognitive feelings in wakefulness, I suggest that white dreaming can sometimes be a metacognitive illusion: A misleading feeling that seems to arise from a dream but could reflect another kind of sleep experience—or none at all.

The scientific study of lucid sleep, defined as the ability to retain critical self-awareness during ongoing sleep, has traditionally focused on lucid dreaming and induction techniques that specifically target REM sleep. Recently, interest has grown to include other forms of lucid sleep, such as out-of-body experiences, sleep paralysis, and “witnessing-sleep” episodes described in Indian philosophical traditions. Empirical data on these states remain limited, primarily due to the lack of specific induction techniques designed for their study. In this case series study, we examine four individuals who reported lucid sleep episodes in a controlled laboratory setting, using a novel induction method combining pre-sleep meditation and visual stimulation. While this method requires future validation, we captured five lucid sleep episodes, including one instance of lucid dreamless sleep, one out-of-body-like experience, and three different types of lucid dreams. Sleep was monitored using wearable EEGs and submental EMGs. A detailed phenomenological analysis provided further context for these experiences, which were reported during both REM and non-REM sleep. Together, the induction protocol and findings described here may inform future research on lucid sleep and altered states of consciousness during sleep.

I introduce a novel multidimensional framework tailored to investigate a set of phenomena that might appear intractable and render them amenable to scientific inquiry. In particular, I focus on examining altered states of consciousness that appear to the experiencing subject as “contentless” or “objectless” states in some form, either by having disrupted or reduced content of awareness, or content that appears as missing altogether. By drawing on empirical research, I propose a cluster of phenomenological dimensions aimed at enhancing our understanding of this group of experiences of minimal awareness, including Richness of the Content, Bodily-Awareness, Passage of Time, Attentional Focus, and Self-Revelation. The result is a robust framework that provides precise scientific terminology, facilitating its operationalisation and adaptability for future empirical work. I show the explanatory power of this framework through a case study of the state of clear light sleep—a state widely reported by Indo-Tibetan Buddhist traditions as an instance of pure awareness during sleep, a state of consciousness-as-such. This rare phenomenon has gained increasing attention in contemporary analytic philosophy of mind for the study of the nature of consciousness. However, we still lack consensus on its characterisation and potential identity with other associated states. I end the paper by illustrating how the state of clear light sleep can be situated in relation to other associated states and more ordinary ones as regions of a multidimensional state space.

This paper presents the results of the first study part of the research project ‘Objectless sleep experiences’ aimed at exploring the phenomenological blueprints of conscious sleep states that lack a distinct object of awareness. A total of 573 responses were collected from an online survey that asked about the incidence, frequency, and phenomenology of a range of sleep phenomena. The survey’s results provide a better understanding of the variety of sleep experiences by yielding preliminary insights into the phenomenology of objectless sleep experiences. Additionally, the results show that putative instances of objectless awareness during sleep are rare. From the thematic analysis, reports of objectless sleep experiences were characterised as a state of “void”, “emptiness”, or simply an awareness of the sleeping state. Moreover, two sorts of temporal dynamics of this sort of experience were distinguished from the reports: following the dissolution of a dream scene or arising spontaneously during sleep without recall of what preceded it. Furthermore, the results provide preliminary insights into the phenomenology of certain waking experiences that some have regarded as potentially related to instances of objectless sleep awareness. Such experiences include the phenomenon of white dreaming, the feeling of knowing, upon awakening, that one had a dream but was unable to recall its content.

I introduce a novel multidimensional framework tailored to investigate a set of phenomena that might appear intractable and render them amenable to scientific inquiry. In particular, I focus on examining altered states of consciousness that appear to the experiencing subject as “contentless” or “objectless” states in some form, either by having disrupted or reduced content of awareness, or content that appears as missing altogether. By drawing on empirical research, I propose a cluster of phenomenological dimensions aimed at enhancing our understanding of this group of experiences of minimal awareness, including “Richness of the Content”, “Bodily-Awareness”, “Passage of Time”, “Attentional Focus”, and “Self-Revelation”. The result is a robust framework that provides precise scientific terminology, facilitating its operationalisation and adaptability for future empirical work. I show the explanatory power of this framework through a case study of the state of clear light sleep—a state widely reported by Indo-Tibetan Buddhist traditions as an instance of pure awareness during sleep, a state of consciousness-as-such. This rare phenomenon has gained increasing attention in contemporary analytic philosophy of mind for the study of the nature of consciousness. However, we still lack consensus on its characterisation and potential identity with other associated states. I end the paper by illustrating how the state of clear light sleep can be situated in relation to other associated states and more ordinary ones as regions of a multidimensional state space.

Recently, the construct ‘lucid dreamless sleep’ has been proposed to explain the state of ‘clear light’ described by Tibetan Buddhist traditions, a special state of consciousness during deep sleep in which we’re told to be able to recognise the nature or essence of our mind (Padmasambhava & Gyatrul 2008; Ponlop 2006; Wangyal 1998). To explain the sort of awareness experienced during this state, some authors have appealed to the sort of lucidity acquired during lucid dreaming and suggested a link between both phenomena (Thompson 2014, 2015; Windt 2015a; Windt et al. 2016). Whilst these authors appeal to a non-conceptually mediated form of lucidity, which doesn’t consist of reflective awareness and propositional thought, the question as to whether the state of clear light should be considered a lucid state similar to lucid dreaming still arises. I argue that the concept ‘lucidity’ used to describe this sort of state is imprecise and that two theoretical notions of lucidity should be distinguished. The first one, which I call the technical notion, requires the recognition of the hallucinatory character of my current experience. The second, the broader notion, involves the seeming recognition of being directly acquainted with the phenomenal character of my experience. I spell out these two notions of lucidity and argue that only the latter could apply to the state of clear light sleep.

Recently, the construct ‘lucid dreamless sleep’ has been proposed to explain the state of ‘clear light’ described by Tibetan Buddhist traditions, a special state of consciousness during deep sleep in which we’re told to be able to recognise the nature or essence of our mind (Padmasambhava & Gyatrul, 2008; Ponlop, 2006; Wangyal, 1998). To explain the sort of awareness experienced during this state, some authors have appealed to the sort of lucidity acquired during lucid dreaming and suggested a link between both phenomena (Thompson, 2014, 2015; Windt, 2015a; Windt et al., 2016). Whilst these authors appeal to a non-conceptually mediated form of lucidity, which doesn’t consist of reflective awareness and propositional thought, the question as to whether the state of clear light should be considered a lucid state similar to lucid dreaming still arises. I argue that the concept ‘lucidity’ used to describe this sort of state is imprecise and that two theoretical notions of lucidity should be distinguished. The first one, which I call the technical notion, requires the recognition of the hallucinatory character of my current experience. The second, the broader notion, involves the seeming recognition of being directly acquainted with the phenomenal character of my experience. I spell out these two notions of lucidity and argue that only the latter could apply to the state of clear light sleep.

Recent years have seen a heightened focus on the study of minimal forms of awareness during sleep to advance the study of consciousness and understand what makes a state conscious. This focus draws on an increased interest in anecdotical descriptions made by classic Indian philosophical traditions about unusual forms of awareness during sleep. For instance, in the so-called state of witnessing-sleep or luminosity sleep, one is said to reach a state that goes beyond ordinary dreaming and abide in a state of just awareness, a state in which one is not aware of anything else other than one’s own awareness. Moreover, for these traditions, this state is taken to be the essence or background of consciousness. Reports on such a state opens the door to exciting new lines of research in the study of consciousness, such as inquiry into the so-called “objectless” awareness during sleep—states of awareness that lack an ordinary object of awareness. In this two-staged research project, we attempted to find the phenomenological blueprints of such forms of awareness during sleep in 18 participants by conducting phenomenological interviews, informed by a novel tool in qualitative research, the micro-phenomenological interview (MPI) method. Following a phenomenological analysis, we isolated a similar phase across 12 reported experiences labelled as ‘nothingness phase’ since it described what participants took to be an experience of ‘nothingness’. his common phase was characterised by minimal sense of self—a bodiless self, yet experienced as being ‘somewhere’—, the presence of non-modal sensations, relatively pleasant emotions, an absence of visual experience, wide and unfocused attention, and an awareness of the state as it unfolded.

This paper presents a pilot study that explores instances of objectless awareness during sleep: conscious experiences had during sleep that prima facie lack an object of awareness. This state of objectless awareness during sleep has been widely described by Indian contemplative traditions and has been characterised as a state of consciousness-as-such; while in it, there is nothing to be aware of, one is merely conscious (cf. Evans-Wentz, 1960; Fremantle, 2001; Ponlop, 2006). While this phenomenon has received diferent names in the literature, such as ‘witnessing-sleep’ and ‘clear light sleep’ among others, the specifc phenomenological profle of this state has not yet been rigorously studied. This paper aims at presenting a preliminary investigation of objectless consciousness during sleep using a novel tool in qualitative research that can guide future research. Five participants experiencing objectless consciousness during sleep were interviewed following the Micro-phenomenological Interview technique (MPI; Petitmengin, 2005, 2006). All participants reported an experience they had during sleep in which there was no scenery and no dream. This period labelled as ‘No Scenery/Void’ was either preceded by the dissolution of a lucid dream or by other forms of conscious mentation. The analysis of the results advances four experiential dimensions during this state of void, namely (1) Perception of absence, (2) Self-perception, (3) Perception of emotions, and (4) Perception of awareness. While the results are primarily explorative, they refer to themes found in the literature to describe objectless sleep and point at potential avenues of research. The results from this study are taken as indications to guide future operationalisations of this phenomenon.

Deep sleep has traditionally been deemed as a period that lack consciousness. However, recent evidence challenges this assumption and highlights the possibility of experiencing awareness during deep sleep. By drawing from Indian philosophical traditions, this thesis defends a positive view of consciousness during dreamless sleep – the period of sleep where we are aware but not dreaming. Moreover, this thesis also challenges classic views on the nature of conscious states where consciousness is reduced to representational content. For that purpose, this thesis develops a taxonomy of dreamless sleep that, contrary to other research in the area, considers the existence of different sorts of awareness with different degrees of content. Thus, a full spectrum of mental states during conscious dreamless sleep are considered: from awareness of substantial content to awareness devoid of content altogether. The aim of the thesis is to show how such a taxonomy can encourage a shift from a two-dimensional view of consciousness to a multidimensional one — from a view that only considers brain activation and reportable content to one that assesses conscious states on different level of analysis. This shift will result in an adequate conceptualisation of dreamless sleep as a period where we could have conscious states with content, but also, conscious states without content. Moreover, this shift on a multidimensional approach will allow us to undertake a proper comparison compare between different sleep phenomena. In order to develop this taxonomy of dreamless sleep, I explore definitions on awareness during dreamless sleep found in Indian philosophical traditions and Western analytical philosophy. From the definitions found in the literature, I argue that all the types of conscious states proposed in my taxonomy can be identified. Then, I test my taxonomy in a pilot study about awareness during deep sleep that I carried out. The results show that the different types of awareness can be recognised in the phenomenological descriptions gathered from the participants. Finally, I compare the phenomenon of dreamless sleep with other associated experiences, such as dreams and hypnagogia. My claim is that the differences among sleep phenomena are gradual and that in some cases there is not a strict cut-off line between them. Notwithstanding this assumption, I defend the development of future research were my proposed taxonomy can be improved by considering typical cases of dreamless sleep.