Limitation of life sustaining therapy in disorders of consciousness: ethics and practice.

Clinical conversations surrounding the continuation or limitation of life-sustaining therapies (LLST) are both challenging and tragically necessary for patients with disorders of consciousness (DoC) following severe brain injury. Divergent cultural, philosophical and religious perspectives contribute to vast heterogeneity in clinical approaches to LLST-as reflected in regional differences and inter-clinician variability. Here we provide an ethical analysis of factors that inform LLST decisions among patients with DoC. We begin by introducing the clinical and ethical challenge and clarifying the distinction between withdrawing and withholding life-sustaining therapy. We then describe relevant factors that influence LLST decision-making including diagnostic and prognostic uncertainty, perception of pain, defining a 'good' outcome, and the role of clinicians. In concluding sections, we explore global variation in LLST practices as they pertain to patients with DoC and examine the impact of cultural and religious perspectives on approaches to LLST. Understanding and respecting the cultural and religious perspectives of patients and surrogates is essential to protecting patient autonomy and advancing goal-concordant care during critical moments of medical decision-making involving patients with DoC.

Memory consolidation of sequence learning and dynamic adaptation during wakefulness.

Motor learning involves acquiring new movement sequences and adapting motor commands to novel conditions. Labile motor memories, acquired through sequence learning and dynamic adaptation, undergo a consolidation process during wakefulness after initial training. This process stabilizes the new memories, leading to long-term memory formation. However, it remains unclear if the consolidation processes underlying sequence learning and dynamic adaptation are independent and if distinct neural regions underpin memory consolidation associated with sequence learning and dynamic adaptation. Here, we first demonstrated that the initially labile memories formed during sequence learning and dynamic adaptation were stabilized against interference through time-dependent consolidation processes occurring during wakefulness. Furthermore, we found that sequence learning memory was not disrupted when immediately followed by dynamic adaptation and vice versa, indicating distinct mechanisms for sequence learning and dynamic adaptation consolidation. Finally, by applying patterned transcranial magnetic stimulation to selectively disrupt the activity in the primary motor (M1) or sensory (S1) cortices immediately after sequence learning or dynamic adaptation, we found that sequence learning consolidation depended on M1 but not S1, while dynamic adaptation consolidation relied on S1 but not M1. For the first time in a single experimental framework, this study revealed distinct neural underpinnings for sequence learning and dynamic adaptation consolidation during wakefulness, with significant implications for motor skill enhancement and rehabilitation.

Structure and Function of Neuronal Circuits Linking Ventrolateral Preoptic Nucleus and Lateral Hypothalamic Area.

To understand how sleep-wakefulness cycles are regulated, it is essential to disentangle structural and functional relationships between the preoptic area (POA) and lateral hypothalamic area (LHA), since these regions play important yet opposing roles in the sleep-wakefulness regulation. GABA- and galanin (GAL)-producing neurons in the ventrolateral preoptic nucleus (VLPO) of the POA (VLPOGABA and VLPOGAL neurons) are responsible for the maintenance of sleep, while the LHA contains orexin-producing neurons (orexin neurons) that are crucial for maintenance of wakefulness. Through the use of rabies virus-mediated neural tracing combined with in situ hybridization (ISH) in male and female orexin-iCre mice, we revealed that the vesicular GABA transporter (Vgat, Slc32a1)- and galanin (Gal)-expressing neurons in the VLPO directly synapse with orexin neurons in the LHA. A majority (56.3 ± 8.1%) of all VLPO input neurons connecting to orexin neurons were double-positive for Vgat and Gal Using projection-specific rabies virus-mediated tracing in male and female Vgat-ires-Cre and Gal-Cre mice, we discovered that VLPOGABA and VLPOGAL neurons that send projections to the LHA received innervations from similarly distributed input neurons in many brain regions, with the POA and LHA being among the main upstream areas. Additionally, we found that acute optogenetic excitation of axons of VLPOGABA neurons, but not VLPOGAL neurons, in the LHA of male Vgat-ires-Cre mice induced wakefulness. This study deciphers the connectivity between the VLPO and LHA, provides a large-scale map of upstream neuronal populations of VLPO→LHA neurons, and reveals a previously uncovered function of the VLPOGABA→LHA pathway in the regulation of sleep and wakefulness.SIGNIFICANCE STATEMENT We identified neurons in the ventrolateral preoptic nucleus (VLPO) that are positive for vesicular GABA transporter (Vgat) and/or galanin (Gal) and serve as presynaptic partners of orexin-producing neurons in the lateral hypothalamic area (LHA). We depicted monosynaptic input neurons of GABA- and galanin-producing neurons in the VLPO that send projections to the LHA throughout the entire brain. Their input neurons largely overlap, suggesting that they comprise a common neuronal population. However, acute excitatory optogenetic manipulation of the VLPOGABA→LHA pathway, but not the VLPOGAL→LHA pathway, evoked wakefulness. This study shows the connectivity of major components of the sleep/wake circuitry in the hypothalamus and unveils a previously unrecognized function of the VLPOGABA→LHA pathway in sleep-wakefulness regulation. Furthermore, we suggest the existence of subpopulations of VLPOGABA neurons that innervate LHA.

Neural complexity and the spectral slope characterise auditory processing in wakefulness and sleep.

Auditory processing and the complexity of neural activity can both indicate residual consciousness levels and differentiate states of arousal. However, how measures of neural signal complexity manifest in neural activity following environmental stimulation and, more generally, how the electrophysiological characteristics of auditory responses change in states of reduced consciousness remain under-explored. Here, we tested the hypothesis that measures of neural complexity and the spectral slope would discriminate stages of sleep and wakefulness not only in baseline electroencephalography (EEG) activity but also in EEG signals following auditory stimulation. High-density EEG was recorded in 21 participants to determine the spatial relationship between these measures and between EEG recorded pre- and post-auditory stimulation. Results showed that the complexity and the spectral slope in the 2-20 Hz range discriminated between sleep stages and had a high correlation in sleep. In wakefulness, complexity was strongly correlated to the 20-40 Hz spectral slope. Auditory stimulation resulted in reduced complexity in sleep compared to the pre-stimulation EEG activity and modulated the spectral slope in wakefulness. These findings confirm our hypothesis that electrophysiological markers of arousal are sensitive to sleep/wake states in EEG activity during baseline and following auditory stimulation. Our results have direct applications to studies using auditory stimulation to probe neural functions in states of reduced consciousness.

How well do neural signatures of resting-state EEG detect consciousness? A large-scale clinical study.

The assessment of consciousness states, especially distinguishing minimally conscious states (MCS) from unresponsive wakefulness states (UWS), constitutes a pivotal role in clinical therapies. Despite that numerous neural signatures of consciousness have been proposed, the effectiveness and reliability of such signatures for clinical consciousness assessment still remains an intense debate. Through a comprehensive review of the literature, inconsistent findings are observed about the effectiveness of diverse neural signatures. Notably, the majority of existing studies have evaluated neural signatures on a limited number of subjects (usually below 30), which may result in uncertain conclusions due to small data bias. This study presents a systematic evaluation of neural signatures with large-scale clinical resting-state electroencephalography (EEG) signals containing 99 UWS, 129 MCS, 36 emergence from the minimally conscious state, and 32 healthy subjects (296 total) collected over 3 years. A total of 380 EEG-based metrics for consciousness detection, including spectrum features, nonlinear measures, functional connectivity, and graph-based measures, are summarized and evaluated. To further mitigate the effect of data bias, the evaluation is performed with bootstrap sampling so that reliable measures can be obtained. The results of this study suggest that relative power in alpha and delta serve as dependable indicators of consciousness. With the MCS group, there is a notable increase in the phase lag index-related connectivity measures and enhanced functional connectivity between brain regions in comparison to the UWS group. A combination of features enables the development of an automatic detector of conscious states.

The impact of sleep on factual memory retention over 24 hr.

Although a period of sleep seems to benefit the retention of declarative memories, recent studies have challenged both the size of this effect and its active influence on memory consolidation. This study aimed to further investigate the effect of sleep and its time dependency on the consolidation of factual information. In a within-subjects design, 48 participants (Mage = 24.37 ± 4.18 years, 31F) were asked to learn several facts in a multi-sensory "flashcard-like" memory task at 21:00 hours (sleep first condition) or at 09:00 hours (wake first condition). Then, in each condition, participants performed an immediate recall test (T0), and two delayed tests 12 hr (T1) and 24 hr (T2) later. Participants' sleep was recorded at their homes with a portable device. Results revealed that memory retention was better after a night of sleep compared with wakefulness, regardless of the delay from encoding (a few hr versus 12+ hr), but the sleep effect was modest. The decline in memory during the wake period following sleep was smaller compared with the decline observed during the 12 hr of wakefulness after encoding. However, after 24 hr from the encoding, when all participants experienced a period of both sleep and wakefulness, memory performance in the two conditions was similar. Overall, our data suggest that sleep exerts a small, yet beneficial, influence on memory retention by likely reducing interference and actively stabilizing memory traces.

Sleep-wake variations of electrodermal activity in bipolar disorder.

BACKGROUND: Affective states influence the sympathetic nervous system, inducing variations in electrodermal activity (EDA), however, EDA association with bipolar disorder (BD) remains uncertain in real-world settings due to confounders like physical activity and temperature. We analysed EDA separately during sleep and wakefulness due to varying confounders and potential differences in mood state discrimination capacities. METHODS: We monitored EDA from 102 participants with BD including 35 manic, 29 depressive, 38 euthymic patients, and 38 healthy controls (HC), for 48 h. Fifteen EDA features were inferred by mixed-effect models for repeated measures considering sleep state, group and covariates. RESULTS: Thirteen EDA feature models were significantly influenced by sleep state, notably including phasic peaks (p < 0.001). During wakefulness, phasic peaks showed different values for mania (M [SD] = 6.49 [5.74, 7.23]), euthymia (5.89 [4.83, 6.94]), HC (3.04 [1.65, 4.42]), and depression (3.00 [2.07, 3.92]). Four phasic features during wakefulness better discriminated between HC and mania or euthymia, and between depression and euthymia or mania, compared to sleep. Mixed symptoms, average skin temperature, and anticholinergic medication affected the models, while sex and age did not. CONCLUSION: EDA measured from awake recordings better distinguished between BD states than sleep recordings, when controlled by confounders.

A role of prefrontal cortico-hypothalamic projections in wake promotion.

Ventromedial prefrontal cortex (vmPFC) processes many critical brain functions, such as decision-making, value-coding, thinking, and emotional arousal/recognition, but whether vmPFC plays a role in sleep-wake promotion circuitry is still unclear. Here, we find that photoactivation of dorsomedial hypothalamus (DMH)-projecting vmPFC neurons, their terminals, or their postsynaptic DMH neurons rapidly switches non-rapid eye movement (NREM) but not rapid eye movement sleep to wakefulness, which is blocked by photoinhibition of DMH outputs in lateral hypothalamus (LHs). Chemoactivation of DMH glutamatergic but not GABAergic neurons innervated by vmPFC promotes wakefulness and suppresses NREM sleep, whereas chemoinhibition of vmPFC projections in DMH produces opposite effects. DMH-projecting vmPFC neurons are inhibited during NREM sleep and activated during wakefulness. Thus, vmPFC neurons innervating DMH likely represent the first identified set of cerebral cortical neurons for promotion of physiological wakefulness and suppression of NREM sleep.

Reliability and validation of the Japanese version of the coma recovery scale-revised (CRS-R).

PRIMARY OBJECTIVE: This study aimed to verify the reliability and validity of the Japanese version of the Coma Recovery Scale-Revised (CRS-R). METHODS: Subjects included 59 patients with disorders of consciousness (DOC) due to acquired brain injury. To validate test-retest reliability, Evaluator A assessed the CRS-R twice on the same day (A1, A2). To examine inter-rater reliability, Evaluators A (A2) and B (B) assessed the CRS-R without a time interval. To test concurrent validity, Evaluator A (A1) assessed the CRS-R, Japan Coma Scale (JCS), and the Glasgow Coma Scale (GCS) consecutively. To validate diagnostic accuracy, we evaluated the degree of agreement between A1 and A2 and between A2 and B in their diagnosis of DOC by CRS-R. RESULTS: The test-retest (ρ = 0.92) and inter- (ρ = 0.98) reliability of CRS-R were excellent" and Concurrent validity of CRS-R with JCS (ρ = -0.82) and GCS (ρ = 0.92) were high. Results of DOC diagnosis were consistent for 48/59 cases (κ = 0.82) for A1 and A2 and for 54/59 cases (κ = 0.92) for A2 and B. CONLCUSION: The Japanese version of the CRS-R may be as reliable and valid as the original English and other language versions.

Long-term repetitive transcranial direct current stimulation in patients with disorders of consciousness: a preliminary study.

OBJECTIVES: To investigate the effects of long-term repetitive transcranial direct current stimulation on patients with DOC in the subacute phase. METHODS: In a randomized, double-blind, controlled study, 33 patients were randomly assigned to the active or sham group, and 28 patients completed the study. Patients in the active group received anodal stimulation over the DLPFC, while patients in the sham group received placebo stimulation (20 min/day, 5 days/week, for 4 weeks). The level of consciousness among patients was assessed with the Coma Recovery Scale-Revised (CRS-R) at baseline and at the end of every week from the first to the fourth week. RESULTS: The CRS-R scores of both the active and sham groups showed a consistent increasing trend over time; however, the treatment effect of the active group was better than that of the sham group. In addition, there was a statistically significant difference in the total CRS-R score between the two groups at weeks 1, 2, 3 and 4. Moreover, 10 patients (71.4%) in the active group and 3 patients (21.4%) in the sham group were regarded as responders. CONCLUSION: Long-term tDCS could improve the level of consciousness of patients with DOC in the subacute stage.

Disclosing Results of Tests for Covert Consciousness: A Framework for Ethical Translation.

The advent of neurotechnologies including advanced functional magnetic resonance imaging and electroencephalography to detect states of awareness not detectable by traditional bedside neurobehavioral techniques (i.e., covert consciousness) promises to transform neuroscience research and clinical practice for patients with brain injury. As these interventions progress from research tools into actionable, guideline-endorsed clinical tests, ethical guidance for clinicians on how to responsibly communicate the sensitive results they yield is crucial yet remains underdeveloped. Drawing on insights from empirical and theoretical neuroethics research and our clinical experience with advanced neurotechnologies to detect consciousness in behaviorally unresponsive patients, we critically evaluate ethical promises and perils associated with disclosing the results of clinical covert consciousness assessments and describe a semistructured approach to responsible data sharing to mitigate potential risks.

Respiratory entrainment of units in the mouse parietal cortex depends on vigilance state.

Synchronous oscillations are essential for coordinated activity in neuronal networks and, hence, for behavior and cognition. While most network oscillations are generated within the central nervous system, recent evidence shows that rhythmic body processes strongly influence activity patterns throughout the brain. A major factor is respiration (Resp), which entrains multiple brain regions at the mesoscopic (local field potential) and single-cell levels. However, it is largely unknown how such Resp-driven rhythms interact or compete with internal brain oscillations, especially those with similar frequency domains. In mice, Resp and theta (θ) oscillations have overlapping frequencies and co-occur in various brain regions. Here, we investigated the effects of Resp and θ on neuronal discharges in the mouse parietal cortex during four behavioral states which either show prominent θ (REM sleep and active waking (AW)) or lack significant θ (NREM sleep and waking immobility (WI)). We report a pronounced state-dependence of spike modulation by both rhythms. During REM sleep, θ effects on unit discharges dominate, while during AW, Resp has a larger influence, despite the concomitant presence of θ oscillations. In most states, unit modulation by θ or Resp increases with mean firing rate. The preferred timing of Resp-entrained discharges (inspiration versus expiration) varies between states, indicating state-specific and different underlying mechanisms. Our findings show that neurons in an associative cortex area are differentially and state-dependently modulated by two fundamentally different processes: brain-endogenous θ oscillations and rhythmic somatic feedback signals from Resp.

Association between neonatal phototherapy and sleep: The Japan Environment and Children's Study.

This observational cohort study aimed to evaluate the association between the duration of neonatal phototherapy and sleep-and-wakefulness states at 1 month, 1.5 years, and 3 years of age. We analysed data from 77,876 infants using the Japan Environment and Children's Study, a nationwide birth cohort study. The participants were divided into three groups: no phototherapy, short phototherapy (1-24 h), and long phototherapy (>24 h). Multiple regression analysis was performed to assess the effect of phototherapy duration on infant sleep at each age after adjusting for potential risk factors. A longer duration of phototherapy was associated with a shorter sleep time over 24 h at 1 month of age (ß, -0.62; SE, -0.77 to -0.47) when compared with a shorter duration of, or no, phototherapy, following the adjustment of confounding factors. Contrastingly, the short duration group, when compared with the no phototherapy group, was associated with later sleep onset (ß, 0.04; SE, 0.00-0.08) and later sleep offset (ß, 0.05; SE, 0.01-0.09) at 1.5 years of age. We concluded that the duration of phototherapy may be transiently associated with sleep duration in infants, as emphasised by the shortening of the total sleep time per 24 h at 1 month of age.

Enhanced phase-amplitude coupling of human electrocorticography selectively in the posterior cortical region during rapid eye movement sleep.

The spatiotemporal dynamics of interaction between slow (delta or infraslow) waves and fast (gamma) activities during wakefulness and sleep are yet to be elucidated in human electrocorticography (ECoG). We evaluated phase-amplitude coupling (PAC), which reflects neuronal coding in information processing, using ECoG in 11 patients with intractable focal epilepsy. PAC was observed between slow waves of 0.5-0.6 Hz and gamma activities, not only during light sleep and slow-wave sleep (SWS) but even during wakefulness and rapid eye movement (REM) sleep. While PAC was high over a large region during SWS, it was stronger in the posterior cortical region around the temporoparietal junction than in the frontal cortical region during REM sleep. PAC tended to be higher in the posterior cortical region than in the frontal cortical region even during wakefulness. Our findings suggest that the posterior cortical region has a functional role in REM sleep and may contribute to the maintenance of the dreaming experience.

Effects of Blindness on Sleep/Wakefulness States in Mice.

To examine the effects of blindness on sleep/wakefulness states, we compared locomotor activity and delayed recovery from isoflurane anesthesia induced by hypnotics during light and dark periods in sighted CBA/N and blind CBA/J mice. Locomotor activity around the switch from the dark to light period significantly differed in both mice. Delayed recovery induced by brotizolam was attenuated in both periods in CBA/J mice. In addition, the period specificity of delayed recovery caused by suvorexant or diphenhydramine in CBA/N mice was abolished in CBA/J mice. These results suggest that blindness impairs sleep quality.

Behavioral scales variability in patients with prolonged disorders of consciousness.

BACKGROUND: The principal conditions differentiating disorders of consciousness (DOC) patients are the unresponsive wakefulness syndrome/vegetative state (UWS/VS) and the minimally conscious state (MCS). Many individuals who suffer from sudden-onset severe brain injury move through stages of UWS/VS and MCS before regaining full awareness. In some patients, the DOC condition is protracted for years (PDOC). In this study, we observed PDOC patients for 6 months to assess possible changes in their level of consciousness. METHODS: We enrolled 40 PDOC patients, 23 UWS/VS and 17 MCS hosted in a dedicated unit for long-term brain injury care. The time from injury was 472 ± 533 days for UWS/VS and 1090 ± 1079 days for MCS. The Wessex Head Injury Matrix (WHIM), Coma Recovery Scale-R (CRS-R), and Nociception Coma Scale were administered monthly for 6 months. RESULTS: During the period of assessment, the percentage of UWS/VS shifted from 58 to 45%, while for the MCS, from 42 to 55%. A positive correlation was found for the UWS/VS patients between the months of observation with the CRS-R total score and WHIM total numbers of behaviors (TNB). In the UWS/VS group, the CRS-R auditive and visual subscales correlated positively with the observation time. During the whole period of observation, 8 patients had constant CRS-R total scores while the WHIM TNB changed in 7 of them. CONCLUSION: Our findings demonstrated that the monthly assessment of PDOC by means of the CRS-R and WHIM was able to detect also subtle changes in consciousness level.

Citizen attitudes to non-treatment decision making: a Norwegian survey.

BACKGROUND: Decisions about appropriate treatment at the end of life are common in modern healthcare. Non-treatment decisions (NTDs), comprising both withdrawal and withholding of (potentially) life-prolonging treatment are in principle accepted in Norway. However, in practice they may give rise to significant moral problems for health professionals, patients and next of kin. Here, patient values must be considered. It is relevant to study the moral views and intuitions of the general population on NTDs and special areas of contention such as the role of next of kin in decision-making. METHODS: Electronic survey to members of a nationally representative panel of Norwegian adults. Respondents were presented with vignettes describing patients with disorders of consciousness, dementia, and cancer where patient preferences varied. Respondents answered ten questions about the acceptability of non-treatment decision making and the role of next of kin. RESULTS: We received 1035 complete responses (response rate 40.7%). A large majority, 88%, supported the right of competent patients to refuse treatment in general. When an NTD was in line with the patient's previously expressed preferences, more respondents tended to find NTDs acceptable. More respondents would accept NTDs for themselves than for the vignette patients. In a scenario with an incompetent patient, clear majorities wanted the views of next of kin to be given some but not decisive weight, and more weight if concordant with the patient's wishes. There were, however, large variations in the respondents' views. CONCLUSION: This survey of a representative sample of the Norwegian adult population indicates that attitudes to NTDs are often in line with national laws and guidelines. However, the high variance among the respondents and relatively large weight given to next of kin's views, indicate a need for appropriate dialogue among all stakeholders to prevent conflicts and extra burdens. Furthermore, the emphasis given to previously expressed opinions indicates that advance care planning may increase the legitimacy of NTDs and prevent challenging decision-making processes.

Contemplating on the Nature of Selfhood in DoC Patients: Neurophenomenological Perspective.

Medical well-regarded policy recommendations for patients with disorders of consciousness (DoC) are almost exclusively relied on behavioural examination and evaluation of higher-order cognition, and largely disregard the patients' self. This is so because practically establishing the presence of self-awareness or Selfhood is even more challenging than evaluating the presence of consciousness. At the same time, establishing the potential (actual physical possibility) of Selfhood in DoC patients is crucialy important from clinical, ethical, and moral standpoints because Selfhood is the most central and private evidence of being an independent and free agent that unites intention, embodiment, executive functions, attention, general intelligence, emotions and other components within the intra-subjective frame (first-person givenness). The importance of Selfhood is supported further by the observation that rebooting of self-awareness is the first step to recovery after brain damage. It seems that complex experiential Selfhood can be plausibly conceptualized within the Operational Architectonics (OA) of brain-mind functioning and reliably measured by quantitative electroencephalogram (qEEG) operational synchrony.

Can the inner eye canthus temperature be used as an alternative method to measure core temperature in sleep-deprived individuals?

Core temperature is used in several situations, including studies on biological rhythms and circadian markers of physical performance. Measuring the inner eye canthus (Tco) temperature is a method proposed to identify core temperature, but it has shown little concordance in physical exercise situations and has not yet been used in studies with measurements taken throughout the day. The objective of this study was to compare the measurements and daily behavior of Tco obtained by infrared thermography with rectal temperature (Tre) during a prolonged waking protocol. Eleven male individuals participated in the study, who remained in the laboratory for at least 38 h using an actigraph to determine the wakefulness time and were monitored during the entire period. The Tre and Tco measurements were performed every 3 h. The ANOVA was used for repeated measurements followed by Bonferroni's post-hoc test to find the limits of concordance/proximity, while the Bland and Altman method and the Intraclass Correlation Coefficient were used to establish the reliability between the pairs. The significance level adopted was p < 0.05. The results demonstrate significant differences, low levels of concordance and unsatisfactory reliability levels between Tco and Tre at all 13 analyzed moments, in addition to not showing measurement reliability when all data are used together with the 143 temperature measurements. Daily behavior analysis shows moments with similar behavior with an increase in Tco and Tre, but at other times the behavior was the opposite, with a decrease in one measurement and an increase in the other. Based on the results presented, it is not recommended to use the inner eye canthus temperature as a substitute for rectal temperature for measuring core temperature at different times of the day or in sleep-deprived individuals.

Region-Specific and State-Dependent Astrocyte Ca2+ Dynamics during the Sleep-Wake Cycle in Mice.

Neural activity is diverse, and varies depending on brain regions and sleep/wakefulness states. However, whether astrocyte activity differs between sleep/wakefulness states, and whether there are differences in astrocyte activity among brain regions remain poorly understood. Therefore, in this study, we recorded astrocyte intracellular calcium (Ca2+) concentrations of mice during sleep/wakefulness states in the cortex, hippocampus, hypothalamus, cerebellum, and pons using fiber photometry. For this purpose, male transgenic mice expressing the genetically encoded ratiometric Ca2+ sensor YCnano50 specifically in their astrocytes were used. We demonstrated that Ca2+ levels in astrocytes substantially decrease during rapid eye movement (REM) sleep, and increase after the onset of wakefulness. In contrast, differences in Ca2+ levels during non-REM (NREM) sleep were observed among the different brain regions, and no significant decrease was observed in the hypothalamus and pons. Further analyses focusing on the transition between sleep/wakefulness states and correlation analysis with the duration of REM sleep showed that Ca2+ dynamics differs among brain regions, suggesting the existence of several clusters, i.e., the first comprising the cortex and hippocampus, the second comprising the hypothalamus and pons, and the third comprising the cerebellum. Our study thus demonstrated that astrocyte Ca2+ levels change substantially according to sleep/wakefulness states. These changes were consistent in general unlike neural activity. However, we also clarified that Ca2+ dynamics varies depending on the brain region, implying that astrocytes may play various physiological roles in sleep.SIGNIFICANCE STATEMENT Sleep is an instinctive behavior of many organisms. In the previous five decades, the mechanism of the neural circuits controlling sleep/wakefulness states and the neural activities associated with sleep/wakefulness states in various brain regions have been elucidated. However, whether astrocytes, which are a type of glial cell, change their activity during different sleep/wakefulness states was poorly understood. Here, we demonstrated that dynamic changes in astrocyte Ca2+ concentrations occur in the cortex, hippocampus, hypothalamus, cerebellum, and pons of mice during natural sleep. Further analyses demonstrated that Ca2+ dynamics slightly differ among different brain regions, implying that the physiological roles of astrocytes in sleep/wakefulness might vary depending on the brain region.