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Neuroscience Letters Feb 2019Arousal plays a central role in a wide variety of phenomena, including wakefulness, autonomic function, affect and emotion. Despite its importance, it remains unclear as... (Review)
Review
Arousal plays a central role in a wide variety of phenomena, including wakefulness, autonomic function, affect and emotion. Despite its importance, it remains unclear as to how the neural mechanisms for arousal are organized across them. In this article, we review neuroscience findings for three of the most common origins of arousal: wakeful arousal, autonomic arousal, and affective arousal. Our review makes two overarching points. First, research conducted primarily in non-human animals underscores the importance of several subcortical nuclei that contribute to various sources of arousal, motivating the need for an integrative framework. Thus, we outline an integrative neural reference space as a key first step in developing a more systematic understanding of central nervous system contributions to arousal. Second, there is a translational gap between research on non-human animals, which emphasizes subcortical nuclei, and research on humans using non-invasive neuroimaging techniques, which focuses more on gross anatomical characterizations of cortical (e.g. network architectures including the default mode network) and subcortical structures. We forecast the importance of high-field neuroimaging in bridging this gap to examine how the various networks within the neural reference space for arousal operate across varieties of arousal-related phenomena.
Topics: Animals; Arousal; Autonomic Nervous System; Brain; Brain Mapping; Brain Stem; Humans; Neuroimaging; Sleep; Wakefulness
PubMed: 29378297
DOI: 10.1016/j.neulet.2018.01.042 -
The Journal of Clinical Psychiatry Aug 2015Research into the sleep-wake cycle has provided new treatment targets for patients with insomnia as well as a better understanding of how medications affect sleep... (Review)
Review
Research into the sleep-wake cycle has provided new treatment targets for patients with insomnia as well as a better understanding of how medications affect sleep processes. Current insomnia medications, including benzodiazepines and nonbenzodiazepines, focus on enhancing sleep-promoting systems through broad antagonism of GABA. Other medications that promote sleep by blocking wake-promoting systems include antidepressants, antipsychotics, and antihistamines, but adverse effects and nonspecific therapeutic effects limit their use. New and emerging insomnia medications are focusing on blocking wake-promoting systems via more selective antagonism of orexin, serotonin, and norepinephrine. These medications may offer improved efficacy with fewer adverse effects.
Topics: Humans; Sleep; Sleep Initiation and Maintenance Disorders; Wakefulness
PubMed: 26335094
DOI: 10.4088/JCP.14046tx2c -
Nature Communications Mar 2024Enhancement of wakefulness is a prerequisite for adaptive behaviors to cope with acute stress, but hyperarousal is associated with impaired behavioral performance....
Enhancement of wakefulness is a prerequisite for adaptive behaviors to cope with acute stress, but hyperarousal is associated with impaired behavioral performance. Although the neural circuitries promoting wakefulness in acute stress conditions have been extensively identified, less is known about the circuit mechanisms constraining wakefulness to prevent hyperarousal. Here, we found that chemogenetic or optogenetic activation of GAD2-positive GABAergic neurons in the midbrain dorsal raphe nucleus (DRN) decreased wakefulness, while inhibition or ablation of these neurons produced an increase in wakefulness along with hyperactivity. Surprisingly, DRN neurons were paradoxically wakefulness-active and were further activated by acute stress. Bidirectional manipulations revealed that DRN neurons constrained the increase of wakefulness and arousal level in a mouse model of stress. Circuit-specific investigations demonstrated that DRN neurons constrained wakefulness via inhibition of the wakefulness-promoting paraventricular thalamus. Therefore, the present study identified a wakefulness-constraining role DRN neurons in acute stress conditions.
Topics: Mice; Animals; Wakefulness; Dorsal Raphe Nucleus; Arousal; Mesencephalon; GABAergic Neurons
PubMed: 38548744
DOI: 10.1038/s41467-024-46707-9 -
Annals of the New York Academy of... Jul 2010The neuropeptides orexin A and orexin B, produced in hypothalamic neurons, are critical regulators of sleep/wake states. Deficiency of orexin signaling results in... (Review)
Review
The neuropeptides orexin A and orexin B, produced in hypothalamic neurons, are critical regulators of sleep/wake states. Deficiency of orexin signaling results in narcoleptic phenotype in humans, dogs, and rodents. Recently, accumulating evidence has indicated that the orexin system regulates sleep and wakefulness through interactions with neuronal systems that are closely related with emotion, reward, and energy homeostasis. In this review, we will discuss the current understanding of the physiology of the orexin system especially focusing on its roles in the regulation of sleep/wakefulness states.
Topics: Animals; Emotions; Energy Metabolism; Homeostasis; Humans; Intracellular Signaling Peptides and Proteins; Motivation; Neuropeptides; Orexins; Sleep; Wakefulness
PubMed: 20633143
DOI: 10.1111/j.1749-6632.2010.05513.x -
Industrial Health Dec 2016Sleep inertia is the period of impaired performance and grogginess experienced after waking. This period of impairment is of concern to workers who are on-call, or nap... (Review)
Review
Sleep inertia is the period of impaired performance and grogginess experienced after waking. This period of impairment is of concern to workers who are on-call, or nap during work hours, and need to perform safety-critical tasks soon after waking. While several studies have investigated the best sleep timing and length to minimise sleep inertia effects, few have focused on countermeasures -especially those that can be implemented after waking (i.e. reactive countermeasures). This structured review summarises current literature on reactive countermeasures to sleep inertia such as caffeine, light, and temperature and discusses evidence for the effectiveness and operational viability of each approach. Current literature does not provide a convincing evidence-base for a reactive countermeasure. Caffeine is perhaps the best option, although it is most effective when administered prior to sleep and is therefore not strictly reactive. Investigations into light and temperature have found promising results for improving subjective alertness; further research is needed to determine whether these countermeasures can also attenuate performance impairment. Future research in this area would benefit from study design features highlighted in this review. In the meantime, it is recommended that proactive sleep inertia countermeasures are used, and that safety-critical tasks are avoided immediately after waking.
Topics: Caffeine; Humans; Light; Melatonin; Sleep; Sound; Temperature; Time Factors; Wakefulness
PubMed: 27193071
DOI: 10.2486/indhealth.2015-0236 -
Sleep Oct 2022Snoozing was defined as using multiple alarms to accomplish waking, and considered as a method of sleep inertia reduction that utilizes the stress system. Surveys...
STUDY OBJECTIVES
Snoozing was defined as using multiple alarms to accomplish waking, and considered as a method of sleep inertia reduction that utilizes the stress system. Surveys measured snoozing behavior including who, when, how, and why snoozing occurs. In addition, the physiological effects of snoozing on sleep were examined via wearable sleep staging and heart rate (HR) activity, both over a long time scale, and on the days that it occurs. We aimed to establish snoozing as a construct in need of additional study.
METHODS
A novel survey examined snoozing prevalence, how snoozing was accomplished, and explored possible contributors and motivators of snoozing behavior in 450 participants. Trait- and day-level surveys were combined with wearable data to determine if snoozers sleep differently than nonsnoozers, and how snoozers and nonsnoozers differ in other areas, such as personality.
RESULTS
57% of participants snoozed. Being female, younger, having fewer steps, having lower conscientiousness, having more disturbed sleep, and being a more evening chronotype increased the likelihood of being a snoozer. Snoozers had elevated resting HR and showed lighter sleep before waking. Snoozers did not sleep less than nonsnoozers nor did they feel more sleepiness or nap more often.
CONCLUSIONS
Snoozing is a common behavior associated with changes in sleep physiology before waking, both in a trait- and state-dependent manner, and is influenced by demographic and behavioral traits. Additional research is needed, especially in detailing the physiology of snoozing, its impact on health, and its interactions with observational studies of sleep.
Topics: Female; Humans; Male; Research Design; Sleep; Sleep Stages; Surveys and Questionnaires; Wakefulness
PubMed: 35951011
DOI: 10.1093/sleep/zsac184 -
Communications Biology Feb 2024The human brain can encode auditory regularities with fixed sound-to-sound intervals and with sound onsets locked to cardiac inputs. Here, we investigated auditory and...
The human brain can encode auditory regularities with fixed sound-to-sound intervals and with sound onsets locked to cardiac inputs. Here, we investigated auditory and cardio-audio regularity encoding during sleep, when bodily and environmental stimulus processing may be altered. Using electroencephalography and electrocardiography in healthy volunteers (Nā=ā26) during wakefulness and sleep, we measured the response to unexpected sound omissions within three regularity conditions: synchronous, where sound and heartbeat are temporally coupled, isochronous, with fixed sound-to-sound intervals, and a control condition without regularity. Cardio-audio regularity encoding manifested as a heartbeat deceleration upon omissions across vigilance states. The synchronous and isochronous sequences induced a modulation of the omission-evoked neural response in wakefulness and N2 sleep, the former accompanied by background oscillatory activity reorganization. The violation of cardio-audio and auditory regularity elicits cardiac and neural responses across vigilance states, laying the ground for similar investigations in altered consciousness states such as coma and anaesthesia.
Topics: Humans; Wakefulness; Electroencephalography; Sleep; Brain; Sound
PubMed: 38396068
DOI: 10.1038/s42003-024-05895-2 -
Sleep Medicine Reviews Aug 2007Averaged event-related potentials (ERPs) represent sensory and cognitive processing of stimuli during wakefulness independent of behavioral responses, and reflect the... (Review)
Review
Averaged event-related potentials (ERPs) represent sensory and cognitive processing of stimuli during wakefulness independent of behavioral responses, and reflect the underlying state of the CNS (central nervous system) during sleep. Components measured during wakefulness which are reflective of arousal state or the automatic switching of attention are sensitive to prior sleep disruption. Components reflecting active attentional influences during the waking state appear to be preserved in a rudimentary form during REM sleep, but in a way that highlights the differences in the neurochemical environment between wakefulness and REM sleep. Certain ERP components only appear within sleep. These begin to emerge at NREM sleep onset and may reflect inhibition of information processing and thus have utility as markers of the functional status of sleep preparatory mechanisms. These large amplitude NREM components represent synchronized burst firing of large number of cortical cells and are a reflection of the nervous system's capacity to generate delta frequency EEG activity. As such they are useful in assessing the overall integrity of the nervous system in populations not showing substantial amounts of SWS as measured using traditional criteria. While requiring care in their interpretation, ERPs nonetheless provide a rich tool to investigators interested in probing the nervous system to evaluate daytime functioning in the face of sleep disruption, the ability of the sleeping nervous system to monitor the external environment, and the ability of the nervous system to respond to stimuli in a manner consistent with the initiation or maintenance of sleep.
Topics: Arousal; Electroencephalography; Event-Related Potentials, P300; Evoked Potentials; Evoked Potentials, Auditory; Humans; Polysomnography; Research Design; Sleep Stages; Sleep, REM; Wakefulness
PubMed: 17628317
DOI: 10.1016/j.smrv.2007.05.001 -
Neuron Sep 2015The state of the brain and body constantly varies on rapid and slow timescales. These variations contribute to the apparent noisiness of sensory responses at both the... (Review)
Review
The state of the brain and body constantly varies on rapid and slow timescales. These variations contribute to the apparent noisiness of sensory responses at both the neural and the behavioral level. Recent investigations of rapid state changes in awake, behaving animals have provided insight into the mechanisms by which optimal sensory encoding and behavioral performance are achieved. Fluctuations in state, as indexed by pupillometry, impact both the "signal" (sensory evoked response) and the "noise" (spontaneous activity) of cortical responses. By taking these fluctuations into account, neural response (co)variability is significantly reduced, revealing the brain to be more reliable and predictable than previously thought.
Topics: Action Potentials; Animals; Brain; Humans; Motor Activity; Nerve Net; Neurons; Time Factors; Wakefulness
PubMed: 26402600
DOI: 10.1016/j.neuron.2015.09.012 -
Journal of Physiological Anthropology Mar 2012The amount and timing of sleep and sleep architecture (sleep stages) are determined by several factors, important among which are the environment, circadian rhythms and... (Review)
Review
The amount and timing of sleep and sleep architecture (sleep stages) are determined by several factors, important among which are the environment, circadian rhythms and time awake. Separating the roles played by these factors requires specific protocols, including the constant routine and altered sleep-wake schedules. Results from such protocols have led to the discovery of the factors that determine the amounts and distribution of slow wave and rapid eye movement sleep as well as to the development of models to determine the amount and timing of sleep. One successful model postulates two processes. The first is process S, which is due to sleep pressure (and increases with time awake) and is attributed to a 'sleep homeostat'. Process S reverses during slow wave sleep (when it is called process S'). The second is process C, which shows a daily rhythm that is parallel to the rhythm of core temperature. Processes S and C combine approximately additively to determine the times of sleep onset and waking. The model has proved useful in describing normal sleep in adults. Current work aims to identify the detailed nature of processes S and C. The model can also be applied to circumstances when the sleep-wake cycle is different from the norm in some way. These circumstances include: those who are poor sleepers or short sleepers; the role an individual's chronotype (a measure of how the timing of the individual's preferred sleep-wake cycle compares with the average for a population); and changes in the sleep-wake cycle with age, particularly in adolescence and aging, since individuals tend to prefer to go to sleep later during adolescence and earlier in old age. In all circumstances, the evidence that sleep times and architecture are altered and the possible causes of these changes (including altered S, S' and C processes) are examined.
Topics: Adolescent; Adult; Age Factors; Aged; Child; Circadian Rhythm; Female; Humans; Male; Middle Aged; Models, Biological; Sleep; Wakefulness
PubMed: 22738268
DOI: 10.1186/1880-6805-31-5