Stage N2 Sleep Research Articles

Pre-sleep social media use does not strongly disturb sleep: a sleep laboratory study in healthy young participants

ObjectiveSleep is critical for our mental health and optimal cognitive functioning. Social media use is increasingly common and suspected to disturb sleep due to increasing bedtime arousal. However, most studies rely on self-reported sleep. MethodsWe tested the effects of 30 min social media use on arousal and subsequent sleep in the sleep laboratory in 32 healthy young volunteers. Effects of blue-light were excluded in this study. We compared it to 30 min progressive muscle relaxation (PMR) and neutral sleep in a within-subject design. ResultsThirty minutes of social media use immediately before sleep did not significantly increase arousal and did neither disturb objective nor subjective sleep. After social media use, participants only spent less time in sleep stage N2. In contrast, PMR had the expected positive effects on pre-sleep arousal level indicated by reduced heart rate. In addition, PMR improved sleep efficiency, reduced sleep onset latency, and shortened the time to reach slow-wave sleep compared to a neutral night. Oscillatory power in the slow-wave activity and spindle bands remained unaffected. ConclusionSocial media use before sleep (controlling for effects of blue-light) had little effect on bedtime arousal and sleep quality than what was previously expected. The most notable effect appears to be the additional time spent engaging in social media use at bedtime, potentially keeping people from going to sleep. As wake up-time is mostly determined externally, due to school or working hours, limiting personal media use at bedtime—and especially in bed—is recommended to get sufficient hours of sleep.

The efficacy of acupuncture on the sleep structure of patients with insomnia: A systematic review and meta-analysis.

This study aims to evaluate the efficacy of acupuncture on the sleep structure of patients with insomnia, so as to provide a valuable basis for the effectiveness of acupuncture in the treatment of insomnia. We conducted searches based on MeSH terms and free words in Cochrane Library, PubMed, Web of science, CKNI (China Knowledge Resource Integrated Database), WanFang Database, and Chongqing VIP Information from the inception of these database until 10 July 2020 for randomized controlled trials (RCTs) that investigated acupuncture treatment in patients with insomnia, and pertinent details of the results were saved. Comprehensive analysis showed that: (1) compared with the Western medicine groups, the acupuncture groups showed significant advantages in reducing the percentage of N1 sleep stage and N2 sleep stage, as well as increasing that of N3 sleep stage and REM sleep stage. However, no significant difference was found in increasing the effective rate, reducing total PSQI score, improving the total sleep time, reducing sleep latency, and improving sleep efficiency between the Western medicine groups and the acupuncture groups. (2) Compared with the sham acupuncture groups, the acupuncture treatment showed advantages in increasing the effective rate, reducing Pittsburgh Sleep Quality Index (PSQI) score, increasing the total sleep time, and improving sleep efficiency. However, no significant difference was observed between the sham acupuncture groups and the acupuncture groups with regard to reducing sleep latency, the percentage of N1 sleep stage and N2 sleep stage, as well as increasing that of N3 sleep stage and REM sleep stage.

Cushing Syndrome is Associated with Increased Stage N2 Sleep and Decreased SWS Partially Reversible After Treatment.

The aim of the present study was to evaluate the sleep parameters of patients with Cushing syndrome (CS) at the time of diagnosis and 12-months after treatment. Thirty four newly diagnosed patients with endogenous CS (17 with ACTH-secreting pituitary adenoma, 17 with adrenal CS) and 23 controls with similar age were included in the study. Two polysomnography (PSG) recordings were performed; one at the time of diagnosis and the other 12 months after resolution of hypercortisolemia. Control group had only baseline PSG. Based on the PSG findings, stage N2 sleep was found to be prolonged, stage N3 and REM sleep were shortened in patients with CS. Average heart rate and mean Apnea Hypopnea Index (AHI) score were higher in patients with CS than the control subjects. Sixteen (47.1%) patients with CS and 4 (17.4%) controls had obstructive sleep apnea (OSA; AHI ≥5). There were no significant differences in sleep parameters of patients according to the etiology of CS (adrenal vs. pituitary) patients. Following 12-months of treatment, a significant decrease in stage N2 sleep and a significant increase in stage N3 sleep were detected, but there was no change in terms of AHI. In conclusion, Cushing syndrome has disturbing effects on sleep structure and these effects are at least partially reversible after treatment. However, the increased risk of OSA was not reversed a year after treatment indicating the importance of early diagnosis and treatment of CS.

Sleep in Intensive Care Unit Patients

Sleep disturbances are common among patients admitted to the intensive care unit (ICU); however, these issues tend to receive less attention because critical care is prioritized in seriously ill patients. Recent studies have reported that sleep disturbances in patients admitted to the ICU are associated with delirium, weakened immunity, long-term cognitive decline, and persistent sleep disorders. Sleep disturbances in the ICU are attributable to the disease per se and also to the ICU environment that is not conducive to good sleep. Continuous exposure to light and noise are major environmental risk factors that disrupt the circadian rhythm and interfere with deep sleep. Sleep analysis using polysomnography in patients admitted to the ICU typically reveals increase in sleep latency, sleep fragmentation, and decreased stage N3 and rapid eye movement sleep, which are associated with poor prognosis even in patients with severe neurological conditions, including traumatic brain injury and intracranial hemorrhage. Polysomnography is the gold standard for objective evaluation of sleep; however, its applicability is limited in ICU settings, and novel methods such as continuous electroencephalographic spectral analysis and actigraphy have recently been proposed in clinical practice. Efforts to reduce nighttime light and noise (which are modifiable environmental factors) can improve sleep quality. In this article, the author reviews the studies that discuss characteristics of sleep disturbances, the associated risk factors and their correlation with prognosis among patients admitted to the ICU, as well as possible strategies to improve sleep quality in this patient population.

Exploring factors associated with interictal heart rate variability in patients with medically controlled focal epilepsy

PurposeHeart rate variability (HRV) reflects the balance between the functional outputs of the sympathetic and parasympathetic nervous systems. It is lower in patients with epilepsy than in the healthy controls. However, HRV has been inadequately studied in different patient subgroups with medically controlled epilepsy. Hence, this study aimed to investigate factors associated with interictal HRV in patients with medically controlled epilepsy. MethodsThis retrospective cohort study included 54 patients (24 males and 30 females) with medically controlled focal epilepsy who only received monotherapy to eliminate the confounding effect of different antiseizure medications (ASMs). Patients with major systemic or psychiatric disorder comorbidities were excluded. For HRV analysis, electroencephalography and 5-minute well-qualified electrocardiogram segment recording were conducted during stage N1 or N2 sleep. In addition, the association between age, gender, seizure onset type, ASMs, and the time domain and frequency-domain HRV measures was analyzed. ResultsHRV negatively correlated with advanced age. Patients with focal to bilateral tonic-clonic seizure (FBTCS) had a significantly lower HRV than focal impaired awareness seizures (FIAS). HRV was not associated with any gender and ASMs. ConclusionsHRV negatively correlated with age, and patients with FBTCS had a decreased HRV. Thus, these patients may have a declining autonomic function. Therefore, different seizure types may carry different risks of autonomic dysfunction in patients with medically controlled focal epilepsy.

Sleep increases leaks and asynchronies during home noninvasive ventilation: a polysomnographic study.

In patients treated with noninvasive ventilation, sleep-related breathing changes can modify patient-ventilator interactions, which could reduce its effectiveness. The aim of this prospective observational study was to determine the impact of sleep/wake state on leaks, upper airway obstructive events, and asynchronies in patients treated by long-term noninvasive ventilation. Stable patients adapted to noninvasive ventilation were considered for nocturnal polysomnography. Unintentional leaks, upper airway obstructive events, and asynchronies were compared between sleep and awake periods. Twenty-eight patients were enrolled. Underlying diagnoses were neuromuscular disease (n = 11), chest wall disease (n = 8), and obesity-hypoventilation (n = 9). Leaks were more frequent in sleep than in awake periods, with a median of 10% (interquartile range [IQR], 0%-75%) vs 1% (IQR, 0%-9%) of time (P < .001), respectively. During sleep, asynchronies with and without associated leak affected 27% of breaths (IQR, 16%-39%) compared with non-leak-related asynchronies that were recorded in 8% (IQR, 3%-25%) of breaths (P < .001). Asynchronies affecting more than 10% of total breaths were more frequent in sleep (25 patients, 89%) than in awake time (8 patients, 29%; P = .25). Eleven patients (39%) presented with 5 or more upper airway obstructive events without reduction in ventilatory drive per hour of sleep. In patients adapted to home noninvasive ventilation, leaks, asynchronies, and upper airway obstructive events are frequent during the night and are concentrated in sleep periods. Asynchronies are often associated with leaks. These findings may have clinical implications considering that in patients with low sleep efficiency respiratory events could be underestimated if sleep is not evaluated. Martí S, Ferré A, Sampol G, etal. Sleep increases leaks and asynchronies during home noninvasive ventilation: a polysomnographic study. J Clin Sleep Med. 2022;18(1):225-233.

Interrater reliability of sleep stage scoring: a meta-analysis.

We evaluated the interrater reliabilities of manual polysomnography sleep stage scoring. We included all studies that employed Rechtschaffen and Kales rules or American Academy of Sleep Medicine standards. We sought the overall degree of agreement and those for each stage. The keywords were "Polysomnography (PSG)," "sleep staging," "Rechtschaffen and Kales (R&K)," "American Academy of Sleep Medicine (AASM)," "interrater (interscorer) reliability," and "Cohen's kappa." We searched PubMed, OVID Medline, EMBASE, the Cochrane library, KoreaMed, KISS, and the MedRIC. The exclusion criteria included automatic scoring and pediatric patients. We collected data on scorer histories, scoring rules, numbers of epochs scored, and the underlying diseases of the patients. A total of 101 publications were retrieved; 11 satisfied the selection criteria. The Cohen's kappa for manual, overall sleep scoring was 0.76, indicating substantial agreement (95% confidence interval, 0.71-0.81; P < .001). By sleep stage, the figures were 0.70, 0.24, 0.57, 0.57, and 0.69 for the W, N1, N2, N3, and R stages, respectively. The interrater reliabilities for stage N2 and N3 sleep were moderate, and that for stage N1 sleep was only fair. We conducted a meta-analysis to generalize the variation in manual scoring of polysomnography and provide reference data for automatic sleep stage scoring systems. The reliability of manual scorers of polysomnography sleep stages was substantial. However, for certain stages, the results were poor; validity requires improvement. Lee YJ, Lee JY, Cho JH, Choi JH. Interrater reliability of sleep stage scoring: a meta-analysis. J Clin Sleep Med. 2022;18(1):193-202.

EEG-Based Demarcation of Yogic and Non-Yogic Sleep Patterns Using Power Spectral Analysis

Electroencephalogram (EEG) signals resulting from recordings of polysomnography play a significant role in determining the changes in physiology and behavior during sleep. This study aims at demarcating the sleep patterns of yogic and non-yogic subjects. Frequency domain features based on power spectral density methods were explored in this study. The EEG recordings were segmented into 1s and 0.5s. EEG patterns with four windowing scheme overlaps (0%, 50%, 60% and 75%) to ensure stationarity of the signal in order to investigate the effect of the pre-processing stage. In order to recognize the yoga and non-yoga group through N3 sleep stage, non-linear KNN classifier was introduced and performance was evaluated in terms of sensitivity and specificity. The experimental results show that modified covariance PSD estimate is the best method in classifying the sleep stage N3 of yogic and non-yogic subjects with 95% confidence interval, sensitivity, specificity and accuracy of 97.3%, 98% and 97%, respectively.

Leg movement activity during sleep in multiple sclerosis with and without restless legs syndrome.

To carry out an analysis of leg movement activity during sleep in a polysomnography dataset of patients with multiple sclerosis (MS) in comparison to idiopathic restless legs syndrome (iRLS) and healthy controls. In this cross-sectional, observational, instrumental study, 57 patients (males/females: 11/46; mean age 46.2 ± 10.2 years) with a diagnosis of MS underwent a telephone interview assessing the 5 standard diagnostic criteria for RLS and polysomnography. Sleep architecture and leg movement activity during sleep were subsequently compared: 1) 40 patients with MS without RLS (MS-RLS) vs 28 healthy controls; 2) 17 patients with MS with RLS (MS+RLS) vs 35 patients with iRLS; 3) MS+RLS vs MS-RLS. MS-RLS and MS+RLS presented increased sleep latency, percentage of sleep stage N1, and reduced total sleep time compared to healthy controls and iRLS, respectively. The periodic limb movements during sleep (PLMS) index was higher in MS-RLS than in healthy controls (P = .035) and lower in MS+RLS compared to iRLS (P = .024). PLMS in MS+RLS were less periodic, less often bilateral, and with shorter single movements compared to the typical PLMS in iRLS. MS is a risk factor for RLS, PLMS, and for a lower sleep quality in comparison to healthy patients. PLMS in MS+RLS are fewer and shorter if compared to iRLS. Our results suggest a dissociation between motor (PLMS) and sensory symptoms (RLS sensory component) in RLS secondary to MS, with possible treatment implications. Ferri R, Sparasci D, Castelnovo A, etal. Leg movement activity during sleep in multiple sclerosis with and without restless legs syndrome. J Clin Sleep Med. 2022;18(1):11-20.

Increased chin muscle tone during all sleep stages in children taking selective serotonin reuptake inhibitor antidepressants and in children with narcolepsy type 1.

To assess if selective serotonin reuptake inhibitor (SSRI) antidepressants are able to modify the chin electromyogram (EMG) tone during sleep also in children. Twenty-three children and adolescents (12 girls, mean age 14.1 years, SD 2.94) under therapy with antidepressant for their mood disorder were consecutively recruited and had a PSG recording. Twenty-one were taking were taking SSRI and treatment duration was 2-12 months. An age- and sex matched group of 33 control children (17 girls, mean age 14.2 years, SD 2.83) and 24 children with narcolepsy type 1 (12 girls, mean age 13.7 years, SD 2.80) were also included. The Atonia Index was then computed for each NREM sleep stage and for REM sleep, also all EMG activations were counted. Atonia Index in all sleep stages was found to be significantly reduced in children with narcolepsy followed by the group taking SSRI antidepressants and the number of EMG activations was also increased in both groups. Fluoxetine, in particular, was found to be significantly associated with reduced Atonia index during NREM sleep stages N1, N2, and N3, and with an increased number of EMG activations/hour during sleep stage N3. Similarly to adults, SSRI antidepressants are able to modify the chin EMG tone in children during REM sleep, as well as during NREM sleep stages. Different pharmacological properties of the different SSRI might explain the differential effect on chin tone during sleep found in this study.

Acute mild dim light at night slightly modifies sleep but does not affect glucose homeostasis in healthy men

ObjectiveWe evaluated the effect of acute mild light exposure at night on sleep architecture and glucose homeostasis. Patients/methodsTwenty healthy normal-weight men took part in two conditions of a randomized, controlled, balanced cross-over experimental study: i) two-consecutive nights with 8-h of sleep under dLAN (<5 lux) or ii) total darkness (CON). Sleep was evaluated by polysomnography. In the morning following 'night2', glucose homeostasis was assessed by an intravenous glucose tolerance test (ivGTT) with consecutive measures of glucose, insulin, and c-peptide. Plasma cortisol was measured at night before sleep, after morning awakening, and during mid-afternoon hours. ResultsThere was no significant difference in total sleep time, sleep efficiency, and sleep latency between conditions (all p > 0.66). However, NREM sleep stage N3 latency was prolonged after dLAN (p = 0.02) and NREM sleep stage 2 was decreased after two nights with dLAN (p = 0.04). During the first sleep hour, power in slow-oscillations, slow-waves, and delta bands diminished after dLAN (all p < 0.04). Glucose, insulin, and c-peptide were not altered by dLAN (all p > 0.14). Cortisol was reduced in the afternoon after 'night1' and in the morning after 'night2' (both p < 0.03). ConclusionsdLAN slightly disturbed sleep architecture and quality without impairment of glucose homeostasis. Longer exposure to chronic dLAN might be needed to unmask its hypothesized metabolic consequences.

Complete sleep evaluation of top professional cross-country mountain bikers' athletes.

Despite growing interest in athletes' sleep, few studies have focused on professional athletes, especially in individual sports. Moreover, limited investigations included female athletes. This study aimed to evaluate sleep chronotype, as well as objective and subjective sleep characteristics in male and female professional cross-country mountain bikers. Thirteen athletes (7 males and 6 females) of the French national team took part in this study. The Chronotype was assessed by the Horne and Östberg Morningness-Eveningness Questionnaire and sleep by actigraphy for one month, by ambulatory polysomnography (PSG) for one night and by the Pittsburgh Sleep Quality Index. Most athletes (77%) are classified as moderately morning type and a minority of athletes (23%) are intermediate type. Athletes sleep on average 8 hours per night and during the night recorded by PSG, N3 and REM sleep stages represented 21.2±3.4% and 20.9±3.1% of the total sleep time, respectively. These good sleep parameters were confirmed by subjective data with 77% good sleepers. Except the poorer subjective sleep quality in female athletes (5.7±1.6) compared to male athletes (2.6±1.7, P<0.05), no significant sex difference was found for all characteristics evaluated. The professional status of these athletes and the organization of mountain bike calendar may explain their good sleep characteristics.

Repetitive sleep starts: An important differential diagnosis of infantile spasms

ObjectiveRepetitive sleep starts (RSS) are clusters of nonepileptic, spasm-like movements occurring during sleep onset. However, their characteristics have yet to be defined. We conducted a clinicoelectroencephalographic study of children with RSS to clarify their detailed characteristics. MethodsTo differentiate starts from epileptic spasms, we recruited children with brief “crescendo–decrescendo” muscle contractions that simultaneously involved the limbs and trunk without electroencephalogram changes, and that fulfilled the following criteria: (1) repeated occurrence (five or more) and (2) manifestation during sleep stage N1–N2. A total of nine children met these criteria. Their clinical information and video-electroencephalogram data were analyzed retrospectively. ResultsThe background conditions observed at onset of RSS were perinatal hypoxic–ischemic encephalopathy (n = 4), West syndrome of unknown etiology (n = 1), and traumatic brain injury (n = 1). The age at onset of RSS, the number of starts in a given RSS cluster, the interval between starts, and the duration of surface electromyogram activity were between 3 and 46 months, 5 and 547, <1 and 60 s, and 0.3 and 5.4 s, respectively. None of the median value of these parameters differed between children with and without corticospinal tract injury. During the median follow-up period of 33 months, RSS disappeared spontaneously in five. ConclusionThis is the largest case series of RSS clarifying their clinicoelectroencephalographic characteristics reported to date. To avoid unnecessary antiepileptic therapies, clinicians should be aware of RSS and distinguish it from other disorders involving involuntary movements or seizures, especially epileptic spasms.

Evening binge alcohol disrupts cardiovagal tone and baroreflex function during polysomnographic sleep.

Binge alcohol consumption is associated with increased cardiovascular risk. The effects of evening binge alcohol consumption (i.e. 4-5 beverages within 2 h) on the vagal components of HRV and cardiovagal baroreflex sensitivity (cvBRS) during sleep remain largely equivocal. The present study examined the effects of evening binge alcohol consumption on nocturnal cardiac vagal tone and baroreflex sensitivity during stage N2, slow wave (SWS), and rapid eye movement (REM) sleep. We hypothesized that evening binge drinking would reduce HRV and cvBRS in each sleep stage. Following a familiarization night within the laboratory, twenty-three participants were examined following a night of binge alcohol consumption and a fluid control (randomized, crossover design). A quality nocturnal beat-to-beat blood pressure signal was obtained in both conditions in 16 participants (seven men, nine women; 25 ± 1 years). Binge drinking reduced both the high frequency (HF) and time-domain components (i.e. pNN50 and RMSSD) of HRV in stage N2 sleep, SWS, and REM. In addition, cvBRS up-up (vagal activation) was reduced following binge alcohol consumption in stage N2 (21 ± 3 vs. 15 ± 3 ms/mmHg, p = 0.035) and REM (15[11-28] vs. 11[9-18] ms/mmHg, p = 0.009). Binge alcohol consumption reduced cvBRS down-down (vagal withdrawal) in stage N2 (23 ± 2 vs. 14 ± 2 ms/mmHg, p < 0.001), SWS (20[14-30] vs. 14[9-17] ms/mmHg, p = 0.022), and REM (14[11-24] vs. 10[7-15] ms/mmHg, p = 0.006). Evening binge alcohol consumption disrupts cardiac vagal tone and baroreflex function during nearly all sleep stages. These findings provide mechanistic insight into the potential role of binge drinking and alcohol abuse on cardiovascular risk. Alcohol and Neural Cardiovascular Control in Binge Drinkers, www.clinicaltrials.gov/ct2/show/NCT03567434, NCT03567434.

The aging slow wave: a shifting amalgam of distinct slow wave and spindle coupling subtypes define slow wave sleep across the human lifespan.

Slow wave and spindle coupling supports memory consolidation, and loss of coupling is linked with cognitive decline and neurodegeneration. Coupling is proposed to be a possible biomarker of neurological disease, yet little is known about the different subtypes of coupling that normally occur throughout human development and aging. Here we identify distinct subtypes of spindles within slow wave upstates and describe their relationships with sleep stage across the human lifespan. Coupling within a cross-sectional cohort of 582 subjects was quantified from stages N2 and N3 sleep across ages 6-88 years old. Results were analyzed across the study population via mixed model regression. Within a subset of subjects, we further utilized coupling to identify discrete subtypes of slow waves by their coupled spindles. Two different subtypes of spindles were identified during the upstates of (distinct) slow waves: an "early-fast" spindle, more common in stage N2 sleep, and a "late-fast" spindle, more common in stage N3. We further found stages N2 and N3 sleep contain a mixture of discrete subtypes of slow waves, each identified by their unique coupled-spindle timing and frequency. The relative contribution of coupling subtypes shifts across the human lifespan, and a deeper sleep phenotype prevails with increasing age. Distinct subtypes of slow waves and coupled spindles form the composite of slow wave sleep. Our findings support a model of sleep-dependent synaptic regulation via discrete slow wave/spindle coupling subtypes and advance a conceptual framework for the development of coupling-based biomarkers in age-associated neurological disease.

803 Sleep Disturbances in Patients with Frontotemporal Dementia

Abstract Introduction Frontotemporal dementia (FTD) is a degenerative process and,as the name implies, involves the frontal and temporal lobes of the brain. Patients with FTD make up 10–15% of all cases of dementia and 20% diagnosed before age 65, however not much is reported about sleep disturbances in these patients. Given the area of neuronal loss one would expect that sleep may be influenced early and by issues in arousal mechanisms and in breathing pattern. This study examined the polysomnography (PSG) reports of patients with a diagnosis FTD. Methods A retrospective chart review was performed to identify patients with both a diagnosis of FTD and having undergone a PSG. 23 patients were identified as fulfilling both requirements. Data recorded included, diagnosis, age at time of PSG, Epworth sleepiness scale (ESS), total sleep time (TST), wake after sleep onset (WASO), sleep latency (SL), REM sleep latency, sleep efficiency (SE), percentage of stage N1, N2, N3, and REM sleep, apnea-hypopnea index (AHI), presence of Cheyne-Stoke breathing, periodic limb movement index, and presence of REM without atonia. Results Patient age ranged from 57–85 years. Average ESS was 8.8 with only 5 patients reported excessive daytime sleepiness(as assessed by ESS). The average TST was 290 minutes, average SL was 37.9 minutes, average WASO was 147.5 minutes, and average sleep efficiency was 60.3%. Patients spent the majority of time in N2 sleep with an average of 68.3% of the time spent in N2. The average time spent in N3 was 9.6% of sleep. 8.9% of sleep was spent in REM. 83% of patients were diagnosed with sleep apnea (as defined by an AHI &amp;gt; 5), with an average AHI of 20.2 events/hour. Cheyne-Stokes breathing was only noted in 4 of the 23 patients, or 17%. Periodic limb movements of sleep were noted in 48% of the patients (n=11). REM without atonia or RBD was not noted for any patients. Conclusion This study shows that patients with FTD suffer from typical sleep disturbances, however there is a high prevalence of sleep apnea as well as PLMS. In addition, patients with FTD have decreased sleep efficiency with increased WASO. Support (if any):

157 The Circadian Variation of Sleep in Postmenopausal Women

Abstract Introduction During menopause, 40-60% of women report sleep complaints. Despite the fact that menopause is associated with fluctuations in sex hormones that can affect circadian physiology, the role of circadian factors in sleep disturbances after menopause is not well understood. The present study aims to understand the circadian variation of sleep occurring after menopause. Methods Eight healthy postmenopausal women (PMW; 54.8±3.4 years, one taking hormones) without sleep complaints were enrolled and compared to previously-collected data from 12 healthy young women (YW; 25.8±3.4 years) in mid-follicular phase. Following an 8-h baseline sleep period aligned to their habitual sleep times, participants underwent a 48-h (PMW) or 72-h (YW) ultradian sleep-wake cycle procedure (USW) with 60-min wake episodes alternating with 60-min nap opportunities. Sleep was recorded with polysomnography. Circadian parameters (amplitude, phase) of core body temperature (CBT) and sleep were assessed and compared using mixed-effects linear models on the first 48 hours of USW. Sleep parameters, including total sleep time (TST), arousals, sleep onset latency (SOL), stages N1, N2, N3, REM, and wake, were compared between groups during baseline and USW. Results PMW presented earlier habitual bedtimes (23:07±00:11 vs 00:13±00:12) and rise-times (07:07±00:11 vs 08:13±00:12) compared to YW (p=0.005). There were no differences in amplitude, phase, or phase angle of CBT. An advanced acrophase of REM sleep (p=0.034) and lower amplitudes of TST, arousals, SOL, N3, and wake, were observed in PMW vs YW (p≤0.05). During baseline, PMW presented more stage N1 (p=0.030) and arousals (p&amp;lt;0.001) than YW. During USW, group effects were observed, with more stage N1 (p=0.007) and N2 (p=0.0007) in PMW vs YW. Significant interactions showed greater TST (p=0.009), shorter SOL (p=0.001), and more arousals (p=0.027) in PMW during the habitual day. Conclusion The primary finding in this small group of PMW with no sleep complaints was a general increase in light sleep and arousals across circadian phases. No differences in CBT rhythms were observed, whereas small differences in the circadian variation of TST, N3, and REM sleep were observed. Further studies are needed to clarify the role of circadian processes on sleep in PMW. Support (if any) Study supported by the Canadian Institutes of Health Research.

513 Young patients with hypersomnia at Tufts Medical Center

Abstract Introduction Young people with hypersomnia (up to 30 years old) represent unique clinical patients that are relatively unstudied. This population has complex presentations, may have increased utilization of medical resources, and have additional and or untreated comorbid conditions such as mild OSA (Obstructive Sleep Apnea). This project looks to characterize and inventory clinical variables of this subset of sleep medicine patients at Tufts Medical Center. In addition, we seek to tabulate management of these patients in order to specifically delineate whether or not treating mild OSA in this group resulted in clinical improvement. Methods After IRB approval, a retrospective database was used to search for patients up to age 30 with comorbid hypersomnia diagnoses from 5/1/2015 to 12/2020. De-indentified datasets, including multiple clinical variables and demographics were analyzed and compared to an age-matched control group of patients who also included an OSA diagnosis. Results Various clinical and demographic data sets were collected in the hypersomnia patient population to characterize the quality and nature of their sleep and hospital utilization. Our preliminary results for this sub-population of 96 patients have found that on average these patients had 2.16 visits to our medical center with some outliers with as many as 6–10 visits in a two-year period from the initial contact. This group had a mean WASO (Wake After Sleep Onset) of 48.95 minutes, a mean sleep latency of 8.56 minutes, and a mean amount of stage N1 sleep of 25.6 minutes (6.4%). Further research will be done to compare these values and more to a similar population with OSA. Conclusion Our retrospective review identifies clinically important data relevant to the sleep quality, patient management, and resource utilization of young patients with hypersomnia. Further research with a comparison to a control group with OSA may identify important differences or nuances between these groups. Support (if any) None

285 Pilot field study of Ambulatory Sleep-Staging in Shift-Working Air Traffic Controllers

Abstract Introduction The simplicity of wrist actigraphy for sleep-wake monitoring in the field contributes to its ubiquity in shift-work research. However, devices based solely on recording activity levels are generally not suitable to quantify sleep architecture. This is a limitation as quantifying changes in sleep stages caused by circadian misalignment is important to better assess the consequences of sleep-wake disruption in shift-working populations. This pilot study was conducted to evaluate whether sleep stages vary with respect to different shift types. Methods Six male air traffic controllers aged 48.5±8.4 years (mean±SD) completed the protocol which entailed two ~9-day periods, each with up to 6 workdays. Schedules comprised 1 or 2 early night shifts (19:30–03:30h), followed by an evening shift (15:00–23:00h), day shift (09:00–17:00h), morning shift (06:30–14:30h), and 1 or 2 full night shifts (23:00–7:00h). A portable sleep-staging device (Somno-Art, Paris, France) that monitored activity levels and heart rate was worn on the non-dominant forearm during bedtime and produced estimates of REM and NREM sleep stages with a proprietary algorithm. Total sleep time (TST) and sleep stages were assessed per shift type with mixed-effects models. Results Final analyses were based on 70 sleep periods preceding workdays, standardized to 24 h to account for the different intervals between consecutive shifts. Analyses revealed significant effects of shift type for TST (p=.016), stages N1 (p=.010) and N2 (p=.043), but none for N3 (p=.055) or REM (p=.117) sleep. TST and stage N1 sleep prior to night shifts was shorter than for day, evening, or early night shifts (all p&amp;lt;.05). Participants obtained less stage N2 sleep prior to night shifts than days shifts (p=.049). Conclusion This pilot study suggests variations in TST across shifts were predominantly due to differences in light sleep stages, whereas no significant differences in N3 and REM sleep were observed. Thus, while TST was reduced for night shifts, participants obtained similar durations of the most recuperative stages. These findings highlight the importance of refined monitoring of sleep in field research involving shift-work. Support (if any) Project funded by NAV Canada. Devices lent by the Somno-Art company. A.K. received a postdoctoral fellowship from the Fonds de Recherche en Santé du Québec (FRQS).

358 Daridorexant Improves Sleep in Patients with Mild/Moderate Obstructive Sleep Apnea

Abstract Introduction Daridorexant is a dual orexin receptor antagonist developed for the treatment of insomnia. The effect of the highest phase-3 dose of 50 mg daridorexant on nighttime respiratory function was evaluated in patients with mild/moderate obstructive sleep apnea (OSA). This study showed that repeated doses of daridorexant had no clinically meaningful effect on the apnea-hypopnea index (AHI) or on peripheral oxygen saturation. In the same study, the effect on objective sleep parameters was also explored by polysomnography (PSG). Methods In this randomized, double-blind, placebo-controlled, two-period, crossover study, daridorexant or placebo was administered in each period once daily for 5 consecutive nights to 28 patients. Treatment difference (daridorexant – placebo) for total sleep time (TST), latency to persistent sleep (LPS), and wake after sleep onset (WASO) was analyzed for Night 5 using linear mixed-effects modeling. In addition, sleep was further explored based on sleep duration during each hour of PSG recording, duration of the different sleep phases (rapid eye movement [REM], non-REM [including N1 to N3 sleep stages]), as well as number and mean/longest duration of awakenings. Results Of 28 patients enrolled, 25 completed the study and were included in the analysis (n=15/10 with mild/moderate OSA; mean [standard deviation] AHI: 16.3 [8.2] events/h). One patient had mild insomnia symptoms at baseline. Compared to placebo, daridorexant prolonged mean TST by 38.8 min (90% confidence interval: 19.7–57.9), shortened mean LPS by 17.2 min (-35.5–1.02), and reduced mean WASO by 31.0 min (-47.3 to 14.7). Sleep architecture was maintained as no treatment differences in the duration of the evaluated sleep stages were observed when normalized to TST. Sleep duration was prolonged in the second part of the night. mean and longest duration of awakenings were decreased by a mean (90% CI) of 2.0 min (-3.1 to 0.9) and 16.3 min (-24.1 to -8.6), respectively, without treatment difference for the total number of awakenings. Conclusion Daridorexant improved objective sleep parameters in patients with mild to moderate OSA without modifying sleep architecture. Support (if any) Funded by Idorsia Pharmaceuticals Ltd.