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The neurobiology of sleep
Published in Philip N. Murphy, The Routledge International Handbook of Psychobiology, 2018
Roman Rutka, Sonia Pellissier, Pascal Hot
The different sleep stages are organized into cycles, and so a sleeper will regularly switch from one stage to the next during a night of sleep. On average, a cycle lasts for around 90 minutes, although the sleep stage structure within each cycle changes as the night progresses; the first half of the night contains a high proportion of SWS and a few short episodes of REM sleep, whereas the second half contains less SWS and more REM sleep. However, around 50% of the total sleep time (TST; i.e., the time interval between sleep onset and final awakening) is spent in NREM-2 sleep. Figure 24.2 depicts a typical hypnogram (i.e., a representation of the changing stages during an episode of sleep), showing that the night is punctuated by several short periods of wakefulness. These usually last no more than a few minutes, and the sleeper does not remember them once he/she has fully woken up. Although these brief awakenings are normal, their overly frequent occurrence is a marker of poor sleep quality. Sleep architecture is influenced by several factors. For example, procedural learning during the day increases the time spent in REM sleep during the following night (Rauchs, Desgranges, Foret, & Eustache, 2005). Furthermore, some disorders, such as depression and post-traumatic stress disorder, are associated with disturbed sleep and specific alterations of the hypnogram. Lastly, as will be discussed below, the characteristics of sleep change over the life span.
Use of Sleep Histogram
Published in Ravi Gupta, S. R. Pandi Perumal, Ahmed S. BaHammam, Clinical Atlas of Polysomnography, 2018
Ravi Gupta, S. R. Pandi Perumal, Ahmed S. BaHammam
The graphical display of the sleep architecture, or sleep stages, along a time axis depicting, is called a hypnogram. However, the graphical display of the sleep stages, sleep-related events and other measured sleep parameters along a time axis, is called histogram. Figures 15.1 and 15.2 shows hypnogram and histogram, respectively.
How can I get more sleep?
Published in Sarah Kuppen, Little Kids, Big Dilemmas, 2018
Stages 3 and 4 are known as deep sleep, where we have slower and more regular heartbeat and breathing. While there is very little whole body movement in deep sleep, it is in these stages where sleep walking can occur. If woken in this stage, your child will be difficult to arouse and will be disoriented and confused. Most stage 3 and 4 sleep occurs towards the beginning of the night. Below is a hypnogram showing typical sleep patterns over a 24 hour period. The diagram makes clear the changes taking place from the ages of three months to two years.
Roza: a new and comprehensive metric for evaluating classification systems
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Researchers working on sleep staging systems to test and compare their proposed systems over other systems frequently use open-access datasets such as sleep-EDF and sleep-EDF expanded (Kemp et al. 2000). The sleep-EDF is the most widely used dataset in sleep staging systems. This dataset, which can be downloaded from the open-access PhysioNet (Goldberger et al. 2000), consists of eight Caucasian men and women aged 21 to 35 years. Of these people, four are healthy (marked as SC and recorded in 1989) and four have mild difficulty falling asleep (marked as ST and recorded in 1994). The subjects did not take any medication before sleeping. EEG recodings were obtained from Fpz-Cz and Pz-Oz channels with the sampling frequency of 100 Hz. According to R&K standards, the signals in this dataset were divided by a clinician into 30-second periods and divided into six sleep stages. Hypnogram data of each person was provided alongside the set. Table 5 shows the number of epochs from eight people per stage.
The Sleep of the Ring: Comparison of the ŌURA Sleep Tracker Against Polysomnography
Published in Behavioral Sleep Medicine, 2019
Massimiliano de Zambotti, Leonardo Rosas, Ian M. Colrain, Fiona C. Baker
Participants wore the ŌURA ring from the time they arrived at the lab until to the next morning and no action was required by them. The ŌURA ring collected data from the participants’ fingers continuously and a proprietary algorithm determined sleep stages (wake, “light”, “deep” and REM sleep). For each night, we calculated the following parameters, which were all aligned with PSG lights-off and lights-on time to match the PSG sleep staging): sleep onset latency (ŌURA-SOL, min), time spent in “deep sleep” (ŌURA-N3, min; equivalent of PSG N3 sleep), time spent in REM sleep (ŌURA-REM, min), time spent in “light sleep” (ŌURA-N1 + N2, min; equivalent of PSG N1 + N2 sleep), total time spent asleep (ŌURA-TST, min; equivalent of PSG TST), and periods of wakefulness after sleep onset (ŌURA-WASO, min; equivalent of PSG WASO). An example of a typical participant’s PSG and ŌURA hypnogram (stages of sleep plotted as a function of time of the night) is provided in Figure 1.
Evaluating pitolisant as a narcolepsy treatment option
Published in Expert Opinion on Pharmacotherapy, 2021
Stefano de Biase, Gaia Pellitteri, Gian Luigi Gigli, Mariarosaria Valente
Pitolisant hydrochloride is a white crystalline powder that is highly soluble in water. Pitolisant is available as film-coated tablets (4.5 and 18 mg) [10]. It binds to the human histamine H3 receptors with high affinity, working as an active antagonist (Ki value of 0.16 nM) and as an inverse agonist (EC50 value of 1.5 nM) [11–13]. It binds other histamine H1, H2, and H4 receptor subtypes with much lower affinities (Ki value >1 μM) [12]. The high affinity for H3 receptors has been confirmed through a positron emission tomography (PET) study in humans. A single oral dose of pitolisant hydrochloride led to the occupancy of 84% of the radiolabelled H3 receptors [14]. H3 receptors are widely distributed in the central nervous system, with predominance in the basal ganglia, hippocampus, hypothalamus, and cortical areas [15]. As an autoreceptor, H3 controls histamine synthesis and release from tuberomammillary neurons, a brain structure involved in the control of wakefulness, attention, learning, and other cognitive functions [16]. Histaminergic neurons, located in the tuberomammillary nucleus in the posterior hypothalamus, are normally triggered by hypocretin neurons of the lateral hypothalamus [17,18]. It has been hypothesized that increasing histaminergic tone by antagonism of the histamine H3 autoreceptor could exert therapeutic effects on EDS [19]. In animals, pitolisant increased hypnogram wake time at the expense of slow-wave and REM sleep, in a dose-dependent manner [20]. Consistently with reduction in direct transitions from wakefulness to REM sleep in murine models, pitolisant showed effectiveness on cataplexy in humans [21]. Although the mechanism of action on this symptom is not fully elucidated, the amygdala, which is strongly involved in cataplexy induction, is strictly modulated by the histaminergic neurons of the tuberomammillary nucleus [22]. Moreover, histaminergic neurons in narcoleptic patients are almost doubled and H3 receptors are highly expressed in the amygdala [18].