Oral Delivered Dexmedetomidine Promotes and Consolidates Non-rapid Eye Movement Sleep via Sleep-Wake Regulation Systems in Mice

Electroencephalographic insights into the pathophysiological mechanisms of emergence delirium in children and corresponding clinical treatment strategies

Emergence delirium is a common postoperative complication in patients undergoing general anesthesia, especially in children. In severe cases, it can cause unnecessary self-harm, affect postoperative recovery, lead to parental dissatisfaction, and increase medical costs. With the widespread use of inhalation anesthetic drugs (such as sevoflurane and desflurane), the incidence of emergence delirium in children is gradually increasing; however, its pathogenesis in children is complex and unclear. Several studies have shown that age, pain, and anesthetic drugs are strongly associated with the occurrence of emergence delirium. Alterations in central neurophysiology are essential intermediate processes in the development of emergence delirium. Compared to adults, the pediatric nervous system is not fully developed; therefore, the pediatric electroencephalogram may vary slightly by age. Moreover, pain and anesthetic drugs can cause changes in the excitability of the central nervous system, resulting in electroencephalographic changes. In this paper, we review the pathogenesis of and prevention strategies for emergence delirium in children from the perspective of brain electrophysiology-especially for commonly used pharmacological treatments-to provide the basis for understanding the development of emergence delirium as well as its prevention and treatment, and to suggest future research direction.

Dexmedetomidine, an alpha 2A receptor agonist, triggers seizures unilaterally in GAERS during the pre-epileptic phase: does the onset of spike-and-wave discharges occur in a focal manner?

Introduction

The genetic absence epilepsy rat from Strasbourg (GAERS) is a rat model for infantile absence epilepsy with spike-and-wave discharges (SWDs). This study aimed to investigate the potential of alpha 2A agonism to induce seizures during the pre-epileptic period in GAERS rats.

Methods

Stereotaxic surgery was performed on male pups and adult GAERS rats to implant recording electrodes in the frontoparietal cortices (right/left) under anesthesia (PN23-26). Following the recovery period, pup GAERS rats were subjected to electroencephalography (EEG) recordings for 2 h. Before the injections, pup epileptiform activity was examined using baseline EEG data. Dexmedetomidine was acutely administered at 0.6 mg/kg to pup GAERS rats 2-3 days after the surgery and once during the post-natal (PN) days 25-29. Epileptiform activities before injections triggered unilateral SWDs and induced sleep durations, and power spectral density was evaluated based on EEG traces.

Results

The most prominent finding of this study is that unilateral SWD-like activities were induced in 47% of the animals with the intraperitoneal dexmedetomidine injection. The baseline EEGs of pup GAERS rats had no SWDs as expected since they are in the pre-epileptic period but showed low-amplitude non-rhythmic epileptiform activity. There was no difference in the duration of epileptiform activities between the basal EEG groups and DEX-injected unilateral SWD-like-exhibiting and non-SWD-like activities groups; however, the sleep duration of the unilateral SWD-like-exhibiting group was shorter. Power spectrum density (PSD) results revealed that the 1.75-Hz power in the left hemisphere peaks significantly higher than in the right.

Discussion

As anticipated, pup GAERS rats in the pre-epileptic stage showed no SWDs. Nevertheless, they exhibited sporadic epileptiform activities. Specifically, dexmedetomidine induced SWD-like activities solely within the left hemisphere. These observations imply that absence seizures might originate unilaterally in the left cortex due to α2AAR agonism. Additional research is necessary to explore the precise cortical focal point of this activity.

Opioid Free Total Intravenous Anesthesia With Dexmedetomidine-Esketamine-Lidocaine for Patients Undergoing Lumpectomy

Background

The aim of the study was to evaluate the feasibility of the opioid-free anesthesia (OFA) technique with dexmedetomidine, esketamine, and lidocaine among patients diagnosed with benign breast mass and scheduled for lumpectomy.

Methods

We enrolled 80 female patients who were aged from 18 to 60 years, graded with American Society of Anesthesiologists physical status I or II, diagnosed with benign breast mass, and scheduled for lumpectomy. These patients were randomly treated with OFA or opioid-based anesthesia (OBA). Dexmedetomidine-esketamine-lidocaine and sufentanil-remifentanil were administered in OFA and OBA group, respectively. We mainly compared the analgesic efficacy of OFA and OBA technique, as well as intraoperative hemodynamics, the quality of recovery, and satisfaction score of patients.

Results

There was no significant difference between the two groups with regard to visual analogue scale (VAS) score at 2, 12, and 24 h after extubation. However, the time to first rescue analgesic was prolonged in OFA group than that in OFB group (6.18 ± 1.00 min vs. 7.40 ± 0.92 min, P = 0.000). Further, mean arterial pressure and heart rate at T0 (entering operating room), T1 (before anesthesia induction), T2 (immediately after intubation), T3, T4, and T5 (1, 5, and 10 min after surgical incision, respectively) were significantly higher in OFA group than that in OBA group. Incidence of hypotension and bradycardia was lower in OFA group. Consistently, fewer patients in OFA group consumed atropine (8% vs. 32%, P = 0.019) and ephedrine (5% vs. 38%, P = 0.001) compared to OBA group. Furthermore, patients in OFA group had a longer awakening time (7.14 ± 2.63 min vs. 4.54 ± 1.14 min, P = 0.000) and recovery time of orientation (11.76 ± 3.15 min vs. 6.92 ± 1.19 min, P = 0.000). Fewer patients in the OFA group experienced postoperative nausea and vomiting (PONV) (11% vs. 51%, P = 0.000) and consumed ondansetron (5% vs. 35%, P = 0.003) compared to OBA group. And patients in OFA group had a higher satisfaction score than those in OBA group (9 (8 - 9) vs. 7 (7 - 8), P = 0.000).

Conclusion

For patients undergoing lumpectomy, OFA technique with dexmedetomidine-esketamine-lidocaine showed a better postoperative analgesic efficacy, a more stable hemodynamics, and a lower incidence of PONV. However, such advantage of OFA technique should be weighed against a longer awakening time and recovery time of orientation in clinical practice.

Dexmedetomidine prevents spatial learning and memory impairment induced by chronic REM sleep deprivation in rats

The study was attempted to investigate the effect on and mechanisms of action of dexmedetomidine with regard to learning and memory impairment in rats with chronic rapid eye movement (REM) sleep deprivation. A total of 50 male Sprague Dawley rats were randomly divided into five groups. Modified multiple platform method was conducted to cause the sleep deprivation of rats. Dexmedetomidine and midazolam were administered by intraperitoneal injection. Learning and memory ability was assessed through Morris water maze. Morphological changes of rat hippocampal neurons and synaptic were detected by transmission electron microscope and Golgi staining. The gene expression in hippocampus of each group was detected by RNA-seq and verified by RT-PCR and western blot. REM Sleep-deprived rats exhibited spatial learning and memory deficits. Furthermore, there was decreased density of synaptic spinous in the hippocampal CA1 region of the sleep deprivation group compared with the control. Additionally, transmission electron microscopy showed that the synaptic gaps of hippocampal neurons in REM sleep deprivation group were loose and fuzzy. Interestingly, dexmedetomidine treatment normalized these events to control levels following REM sleep deprivation. Molecular biological methods showed that Alox15 expression increased significantly after REM sleep deprivation as compared to control, while dexmedetomidine administration reversed the expression of Alox15. Dexmedetomidine alleviated the spatial learning and memory dysfunction induced with chronic REM sleep deprivation in rats. This protective effect may be related to the down-regulation of Alox15 expression and thereby the enhancement of synaptic structural plasticity in the hippocampal CA1 area of rats.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41105-023-00450-8.

Dexmedetomidine in Psychiatry: Repurposing of its Fast-Acting Anxiolytic, Analgesic and Sleep Modulating Properties

Drug repurposing is a strategy to identify new indications for already approved drugs. A recent successful example in psychiatry is ketamine, an anesthetic drug developed in the 1960s, now approved and clinically used as a fast-acting antidepressant. Here, we describe the potential of dexmedetomidine as a psychopharmacological repurposing candidate. This α₂-adrenoceptor agonist is approved in the US and Europe for procedural sedation in intensive care. It has shown fast-acting inhibitory effects on perioperative stress-related pathologies, including psychomotor agitation, hyperalgesia, and neuroinflammatory overdrive, proving potentially useful in clinical psychiatry. We offer an overview of the pharmacological profile and effects of dexmedetomidine with potential utility for the treatment of neuropsychiatric symptoms. Dexmedetomidine exerts fast-acting and robust sedation, anxiolytic, analgesic, sleep-modulating, and anti-inflammatory effects. Moreover, the drug prevents postoperative agitation and delirium, possibly via neuroprotective mechanisms. While evidence in animals and humans supports these properties, larger controlled trials in clinical samples are generally scarce, and systematic studies with psychiatric patients do not exist. In conclusion, dexmedetomidine is a promising candidate for an experimental treatment targeting stress-related pathologies common in neuropsychiatric disorders such as depression, anxiety disorders, and posttraumatic stress disorder. First small proof-of-concept studies and then larger controlled clinical trials are warranted in psychiatric populations to test the feasibility and efficacy of dexmedetomidine in these conditions.

Overlooked switch from transient sedation to sustained excitement in the Biphasic effects of Ephedra Herb extract administered orally to mice

ETHNOPHARMACOLOGICAL RELEVANCE

In our previous study, we reported that Ephedra Herb extract (EHE) increased the locomotor activity of mice in the open-field test and reduced the immobility time in the forced swim test. Ephedrine alkaloids (EAs) are thought to be responsible for the adverse effects of Ephedra Herb. However, there are no reports to verify that the adverse effects of Ephedra Herb are caused by the amount of EAs in the herb. Therefore, we investigated whether these adverse effects of EHE are caused by the amounts of ephedrine (Eph) and pseudoephedrine (Pse) in the herbal extract. In a preliminary study of the time course analysis of the open field test, we newly observed that EHE evoked switching from transient sedation to sustained excitement.

AIM OF THE STUDY

We aimed to confirm whether EHE evokes switching from transient sedation to sustained excitement, investigate whether these actions of EHE are caused by the amount of ephedrine (Eph) and pseudoephedrine (Pse) in the herbal extract, and clarify the molecular mechanism of the transient sedative effect.

MATERIALS AND METHODS

The locomotor activity of mice was tested using the open-field test. The immobility times were measured using a forced swim test, and the motor dysfunction in mice was tested using the rotarod test.

RESULTS

EHE, Eph, and Pse induced transient motionlessness between 0 and 15 min after oral administration, however, they did not induce depression-like behavior and motor dysfunction in mice, suggesting that the motionlessness induced by EHE, Eph, or Pse resulted from sedation. The α2a adrenoceptor inhibitor, atipamezole, decreased their sedative effects. Thus, immediately after EHE administration, the transient sedative effect is mediated through the activation of the α2a adrenoreceptor by Eph and Pse. EHE and Eph increased total locomotor activity for 15-120 min after oral administration; however, Pse had no effect. Therefore, the slow-onset and sustained excitatory effects of EHE are mediated by Eph.

CONCLUSIONS

We discovered for the first time that EHE evokes diphasic action by switching from transient sedation to sustained excitement. The transient sedation was evoked by the Eph and Pse in the herbal extract via activation of the α2a adrenoceptor and the sustained excitement was caused by the Eph in the herbal extract.

Shumian Capsule Improves the Sleep Disorder and Mental Symptoms Through Melatonin Receptors in Sleep-Deprived Mice

Healthy sleep is vital to maintaining the body's homeostasis. With the development of modern society, sleep disorder has gradually become one of the most epidemic health problems worldwide. Shumian capsule (SMC), a kind of traditional Chinese medicine (TCM) commonly used for insomnia, exhibits antidepressant and sedative effects in clinical practice. However, the underlying mechanisms have not been fully clarified. With the aid of a network pharmacology approach and function enrichment analysis, we identified the involvement of melatonin receptors in the antidepressant and sedative effects of SMC. In sleep-deprived mice, SMC treatment significantly alleviated insomnia and relevant mental alterations by improving both sleep latency and sleep duration. However, ramelteon, a selective melatonin receptor agonist that has been approved for the treatment of insomnia, only improved sleep latency. Additionally, SMC exhibited comparable effects on mental alterations with ramelteon as determined by an open-field test (OFT) and forced swimming test (FST). Mechanistically, we revealed that the melatonin receptor MT1 and MT2 signaling pathways involved the therapeutic effects of SMC. In addition to the single effect of traditional melatonin receptor agonists on treating sleep onset insomnia, SMC had therapeutic potential for various sleep disorders, such as sleep onset insomnia and sleep maintenance insomnia. Convergingly, our findings provide theoretical support for the clinical application of SMC.

Sleep Spindles and K-Complexes Are Favorable Prognostic Biomarkers in Critically Ill Patients

SUMMARY

In this narrative review, we summarize recent research on the prognostic significance of biomarkers of sleep in continuous EEG and polysomnographic recordings in intensive care unit patients. Recent studies show the EEG biosignatures of non-rapid eye movement 2 sleep (sleep spindles and K-complexes) on continuous EEG in critically ill patients better predict functional outcomes and mortality than the ictal-interictal continuum patterns. Emergence of more complex and better organized sleep architecture has been shown to parallel neurocognitive recovery and correlate with functional outcomes in traumatic brain injury and strokes. Particularly interesting are studies which suggest intravenous dexmedetomidine may induce a more biomimetic non-rapid eye movement sleep state than intravenous propofol, potentially providing more restorative sleep and lessening delirium. Protocols to improve intensive care unit sleep and neurophysiological studies evaluating the effect of these on sleep and sleep architecture are here reviewed.

A randomized placebo-controlled double-blind study of dexmedetomidine on postoperative sleep quality in patients with endoscopic sinus surgery

Background

Postoperative sleep disorder is common and may cause aggravated postoperative pain, delirium, and poor prognosis. We accessed the effect of intraoperative intravenous dexmedetomidine on postoperative sleep quality in patients with endoscopic sinus surgery. 

Methods

This single-center, double-blind, placebo-controlled randomized clinical trial enrolled a total of 110 participants aged 18 years to 65 years who were scheduled to receive endoscopic sinus surgery. Placebo (normal saline) or dexmedetomidine infusion (load dose 0.5 μg kg⁻¹ over 10 min, followed by maintenance dose 0.2 ug kg⁻¹ h⁻¹) during surgery. The primary outcome was postoperative sleep quality. Secondary outcomes were postoperative Ramsay sedation scores, Visual Analog Scale (VAS) scores, serum cortisol, 5-hydroxytryptamine (5-HT) and hypocretin, delirium, and postoperative nausea and vomiting (PONV).

Results

Among enrolled 110 patients, 55 were randomized to administer intraoperative dexmedetomidine and placebo. In total, 14 patients (7 in each group) were excluded because of protocol deviations, and 96 patients (48 in each group) were included in the per-protocol analysis. The dexmedetomidine group had a significantly higher sleep efficiency index(SEI) (66.85[3.00] vs 65.38[3.58]), the ratio of rapid eye movement sleep to total sleep(REM)(13.63[1.45] vs 12.38[2.11]) and lower arousal index (AI) (7.20[1.00] vs 8.07[1.29]), higher Ramsay sedation score at post-operation 1 h, 12 h point, lower VAS scores at post-operation 1 h, 12 h, 24 h point, lower cortisol, higher 5-HT and hypocretin in serum than the placebo group.

Conclusion

In this randomized clinical trial, dexmedetomidine can improve the sleep quality of patients undergoing endoscopic sinus surgery. These results suggest that this therapy may be a viable strategy to enhance postoperative sleep quality in patients with endoscopic sinus surgery.

Trial registration

The study was approved by the Bethune International Peace Hospital Ethics Committee (2021-KY-129) and registered in the Chinese Clinical Trial Registry (ChiCTR2100051598, 28/09/2021). 

Oxytocin normalizes altered circuit connectivity for social rescue of the Cntnap2 knockout mouse

The neural basis of abnormal social behavior in autism spectrum disorders (ASDs) remains incompletely understood. Here we used two complementary but independent brain-wide mapping approaches, mouse resting-state fMRI and c-Fos-iDISCO+ imaging, to construct brain-wide activity and connectivity maps of the Cntnap2 knockout (KO) mouse model of ASD. At the macroscale level, we detected reduced functional coupling across social brain regions despite general patterns of hyperconnectivity across major brain structures. Oxytocin administration, which rescues social deficits in KO mice, strongly stimulated many brain areas and normalized connectivity patterns. Notably, chemogenetically triggered release of endogenous oxytocin strongly stimulated the nucleus accumbens (NAc), a forebrain nucleus implicated in social reward. Furthermore, NAc-targeted approaches to activate local oxytocin receptors sufficiently rescued their social deficits. Our findings establish circuit- and systems-level mechanisms of social deficits in Cntnap2 KO mice and reveal the NAc as a region that can be modulated by oxytocin to promote social interactions.

Involvement of the adenosine A1 receptor in the hypnotic effect of rosmarinic acid

Insomnia, the most common sleep disorder, is characterized by a longer sleep latency, greater sleep fragmentation, and consequent excessive daytime fatigue. Due to the various side effects of prescribed hypnotics, demand for new drugs is still high. Recent studies have suggested the adenosine receptor (AR) as a potential therapeutic target for insomnia, however, clinically useful hypnotics targeting AR are not yet available. In the present study, we evaluated the hypnotic effect of rosmarinic acid, a phenolic compound widely found in medicinal plants, through pentobarbital-induced sleep test, electroencephalography/electromyography (EEG/EMG), and immunohistochemistry in mice. The underlying mechanisms were assessed by pharmacological approach using 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and SCH5826, antagonists for A1R and A2AR, respectively. Receptor-binding assay and functional agonism were also performed. Our study provides a new evidence that rosmarinic acid has a direct binding activity (Ki = 14.21 ± 0.3 μM) and agonistic activity for A1R. We also found that rosmarinic acid significantly decreased sleep fragmentation and onset latency to NREM sleep, and these effects were abolished by DPCPX. The results from c-Fos immunostaining showed that rosmarinic acid decreased the neuronal activity in wake-promoting brain regions, such as the basal forebrain and the lateral hypothalamus, while increasing the neuronal activity in the ventrolateral preoptic nucleus, a sleep-promoting region; all these effects were significantly inhibited by DPCPX. Taken together, this study suggests that rosmarinic acid possesses novel activity as an A1R agonist and thereby exerts a hypnotic effect, and thus it may serve as a potential therapeutic agent for insomnia through targeting A1R.

Effect of partial and total sleep deprivation on serum testosterone in healthy males: a systematic review and meta-analysis

BACKGROUND

Currently, there is no consensus on the effect of sleep deprivation on male serum testosterone. This systematic review and meta-analysis aimed to determine the association between partial/total sleep deprivation and male serum testosterone level.

METHODS

The literature related to sleep deprivation and male serum testosterone in the PubMed, Embase, and Cochrane Library databases were searched from their inception to July 15, 2021. Data were pooled using the Stata 15 software. The results were presented as standard mean differences (SMDs) with their 95% confidence intervals (CIs).

RESULTS

Eighteen studies involving 252 men were included in the systematic review and meta-analysis. The findings revealed that short-term partial sleep deprivation had no significant effect on male serum testosterone (SMD = -0.22; 95% CI: -0.5, 0.06; P = 0.13), while total sleep deprivation reduced the male testosterone levels (SMD = -0.64; 95% CI: -0.87, -0.42; P < 0.001). According to the intervention duration of total sleep deprivation, subgroup analysis was conducted by a fixed-effects model. The results revealed that the serum testosterone was significantly decreased after 24 h total sleep deprivation (SMD = - 0.67; 95% CI = - 0.93, -0.42, P < 0.001), as well as 40-48 h total sleep deprivation (SMD = - 0.74; 95% CI = - 1.22, -0.26, P = 0.002).

CONCLUSIONS

This meta-analysis revealed that total sleep deprivation (more than or equal to 24 h) reduces the male testosterone levels, while short-term partial sleep deprivation has no significant effect on male serum testosterone. Sleep duration plays a pivotal role in maintaining male serum testosterone levels.

Role of NR2B/ERK signaling in the neuroprotective effect of dexmedetomidine against sevoflurane induced neurological dysfunction in the developing rat brain

Dexmedetomidine (DEX) is a potent α‑2 adrenergic receptor agonist and has been widely applied in clinic. The present study explored the protective effect of DEX on sevoflurane‑induced learning and cognitive impairment and examined its underlying mechanism. Sprague‑Dawley rat pups were exposed to 0.85% sevoflurane for 6 h and injected with DEX in different doses. The Morris water maze test was performed to evaluate the learning and memory function of rats. Western blot was used for the measurement of protein levels. The water maze results indicated that sevoflurane treatment increased the escape latency but reduced the time spent in the original quadrant of rats. The protein levels of NR2B, phosphorylated ERK were significantly influenced by sevoflurane. Ifenprodil administration alleviated sevoflurane‑induced neurological impairment. DEX treatment reversed the effect of sevoflurane on both escape latency and time in original quadrant in a dose manner, and pretreatment with DEX had the most dramatic effect. DEX regulated the NR2B/ERK signaling in sevoflurane treated rats. NR2B/ERK signaling is involved in sevoflurane induced neurological impairment. DEX may protect against sevoflurane induced neurological dysfunction in the developing rat brain via regulating the NR2B/ERK signaling.

Identifying c-fos Expression as a Strategy to Investigate the Actions of General Anesthetics on the Central Nervous System

Although general anesthetics have been used in the clinic for more than 170 years, the ways in which they induce amnesia, unconsciousness, analgesia, and immobility remain elusive. Modulations of various neural nuclei and circuits are involved in the actions of general anesthetics. The expression of the immediate-early gene c-fos and its nuclear product, c-fos protein, can be induced by neuronal depolarization; therefore, c-fos staining is commonly used to identify the activated neurons during sleep and/or wakefulness, as well as in various physiological conditions in the central nervous system. Identifying c-fos expression is also a direct and convenient method to explore the effects of general anesthetics on the activity of neural nuclei and circuits. Using c-fos staining, general anesthetics have been found to interact with sleep- and wakefulness-promoting systems throughout the brain, which may explain their ability to induce unconsciousness and emergence from general anesthesia. This review summarizes the actions of general anesthetics on neural nuclei and circuits based on a c-fos expression.

Effect of Dexmedetomidine on Postoperative Sleep Quality: A Systematic Review

In this article, we conduct a systematic review of the literature to explore the specific role of dexmedetomidine (DEX) on postoperative sleep and its associated mechanisms at present. The electronic database Embase, MEDLINE/PubMed, the Cochrane Library, Web of Science, and Google Scholar were searched. The restriction terms included “dexmedetomidine”, “sleep” and “surgery”. The inclusion criteria were as following: 1) patients 18 years old or older; 2) DEX used in the perioperative period not just for critically ill patients in the intensive care unit (ICU); 3) prospective or retrospective studies. The review articles, conference abstracts, and animal studies were excluded. Out of the 22 articles which met the above criteria, 20 of them were randomized controlled studies and 2 of them were retrospective cohort studies. Infusion of DEX including during the surgery and after surgery at a low or high dose was shown to improve subjective and objective sleep quality, although 2 studies showed there is no evidence that the use of DEX improves sleep quality and 1 showed less sleep efficiency and shorter total sleep time in the DEX group. Other postoperative outcomes evaluated postoperative nausea and vomiting, pain, postoperative delirium bradycardia and hypotension. Outcomes of our systematic review showed that DEX has advantages in improving patients’ postoperative sleep quality. Combined with the use of general anesthetic, DEX provides a reliable choice for procedural sedation.

Roles of motor and cortical activity in sleep rebound in rat

Sleep pressure that builds up gradually during the extended wakefulness results in sleep rebound. Several lines of evidence, however, suggest that wake per se may not be sufficient to drive sleep rebound and that rapid eye movement (REM) and non-rapid eye movement (NREM) sleep rebound may be differentially regulated. In this study, we investigated the relative contribution of brain versus physical activities in REM and NREM sleep rebound by four sets of experiments. First, we forced locomotion in rats in a rotating wheel for 4 hr and examined subsequent sleep rebound. Second, we exposed the rats lacking homeostatic sleep response after prolonged quiet wakefulness and arousal brain activity induced by chemoactivation of parabrachial nucleus to the same rotating wheel paradigm and tested if physical activity could rescue the sleep homeostasis. Third, we varied motor activity levels while concurrently inhibiting the cortical activity by administering ketamine or xylazine (motor inhibitor), or ketamine + xylazine mixture and investigated if motor activity in the absence of activated cortex can cause NREM sleep rebound. Fourth and finally, we manipulated cortical activity by administering ketamine (that induced active wakefulness and waking brain) alone or in combination with atropine (that selectively inhibits the cortex) and studied if cortical inhibition irrespective of motor activity levels can block REM sleep rebound. Our results demonstrate that motor activity but not cortical activity determines NREM sleep rebound whereas cortical activity but not motor activity determines REM sleep rebound.