SLEEP

Kohno, Akane; Kohno, Masaki; Ohkoshi, Shogo

doi: 10.1093/sleep/zsac036pmid: 35167701

Study ObjectivesThere are only a few reports on voluntary swallowing during sleep; therefore, this study aimed to propose a method for observing voluntary swallowing during sleep using polysomnography. The frequency of voluntary swallowing during sleep and the factors related to swallowing and aspiration during sleep were investigated.MethodsPolysomnography records of 20 control subjects and 60 patients with obstructive sleep apnea (OSA) (mild, moderate, and severe groups; n = 20 each) were collected. Simultaneous increases in the electromyographic potentials of the submental and masseter muscles, termed coactivation, and declining oronasal airflow (SA) were extracted as “swallowing.” The cough reflex that occurred during sleep was extracted as “aspiration.” The frequency of swallowing events was compared among the different OSA severity groups. Subsequently, a multivariate regression analysis was performed.ResultsThe average frequency of coactivation with SA in control subjects was 4.1 events/h and that without SA was 1.7 events/h. These frequencies increased with the severity of OSA during non-REM sleep. The distance of the hyoid to the Frankfurt plane was associated with the frequency of coactivation with (β = 0.298, p = 0.017) as well as without SA (β = 0.271, p = 0.038). The frequency of coactivation without SA was associated with aspiration (B = 0.192, p = 0.042).ConclusionsOur data provide new insights into the relationship between swallowing and aspiration during sleep. We found that the longer the distance from the hyoid bone to the Frankfurt plane, the higher the coactivation without SA, which could lead to aspiration during sleep.Clinical TrialsRetrospective observational study of swallowing during sleep in obstructive sleep apnea patients using polysomnography, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000050460, UMIN000044187.

Aghayan Golkashani, Hosein; Leong, Ruth L F; Ghorbani, Shohreh; Ong, Ju Lynn; Fernández, Guillén; Chee, Michael W L

doi: 10.1093/sleep/zsac025pmid: 35090173

Study ObjectivesThe learning brain establishes schemas (knowledge structures) that benefit subsequent learning. We investigated how sleep and having a schema might benefit initial learning followed by rearranged and expanded memoranda. We concurrently examined the contributions of sleep spindles and slow-wave sleep to learning outcomes.MethodsFifty-three adolescents were randomly assigned to an 8 h Nap schedule (6.5 h nocturnal sleep with a 90-minute daytime nap) or an 8 h No-Nap, nocturnal-only sleep schedule. The study spanned 14 nights, simulating successive school weeks. We utilized a transitive inference task involving hierarchically ordered faces. Initial learning to set up the schema was followed by rearrangement of the hierarchy (accommodation) and hierarchy expansion (assimilation). The expanded sequence was restudied. Recall of hierarchical knowledge was tested after initial learning and at multiple points for all subsequent phases. As a control, both groups underwent a No-schema condition where the hierarchy was introduced and modified without opportunity to set up a schema. Electroencephalography accompanied the multiple sleep opportunities.ResultsThere were main effects of Nap schedule and Schema condition evidenced by superior recall of initial learning, reordered and expanded memoranda. Improved recall was consistently associated with higher fast spindle density but not slow-wave measures. This was true for both nocturnal sleep and daytime naps.ConclusionA sleep schedule incorporating regular nap opportunities compared to one that only had nocturnal sleep benefited building of robust and flexible schemas, facilitating recall of the subsequently rearranged and expanded structured knowledge. These benefits appear to be strongly associated with fast spindles.Clinical Trial registrationNCT04044885 (https://clinicaltrials.gov/ct2/show/NCT04044885).

Lo, June Chi-Yan; Koa, Tiffany B; Ong, Ju Lynn; Gooley, Joshua J; Chee, Michael W L

doi: 10.1093/sleep/zsac023pmid: 35089345

Study ObjectivesWe characterized vigilance deterioration with increasing time-on-task (ToT) during recurrent sleep restriction of different extents on simulated weekdays and recovery sleep on weekends, and tested the effectiveness of afternoon napping in ameliorating ToT-related deficits.MethodsIn the Need for Sleep studies, 194 adolescents (age = 15–19 years) underwent two baseline nights of 9-h time-in-bed (TIB), followed by two cycles of weekday manipulation nights and weekend recovery nights (9-h TIB). They were allocated 9 h, 8 h, 6.5 h, or 5 h of TIB for nocturnal sleep on weekdays. Three additional groups with 5 h or 6.5 h TIB were given an afternoon nap opportunity (5 h + 1 h, 5 h + 1.5 h, and 6.5 h + 1.5 h). ToT effects were quantified by performance change from the first 2 min to the last 2 min in a 10-min Psychomotor Vigilance Task administered daily.ResultsThe 9 h and the 8 h groups showed comparable ToT effects that remained at baseline levels throughout the protocol. ToT-related deficits were greater among the 5 h and the 6.5 h groups, increased prominently in the second week of sleep restriction despite partial recuperation during the intervening recovery period and diverged between these two groups from the fifth sleep-restricted night. Daytime napping attenuated ToT effects when nocturnal sleep restriction was severe (i.e. 5-h TIB/night), and held steady at baseline levels for a milder dose of nocturnal sleep restriction when total TIB across 24 h was within the age-specific recommended sleep duration (i.e. 6.5 h + 1.5 h).ConclusionsReducing TIB beyond the recommended duration significantly increases ToT-associated vigilance impairment, particularly during recurrent periods of sleep restriction. Daytime napping is effective in ameliorating such decrement.Clinical Trial RegistrationNCT02838095, NCT03333512, and NCT04044885.

Wilson, Danielle L; Fung, Alison M; Pell, Gabrielle; Skrzypek, Hannah; Barnes, Maree; Bourjeily, Ghada; Walker, Susan P; Howard, Mark E

doi: 10.1093/sleep/zsac032pmid: 35150285

Links between supine “going to sleep” position and stillbirth risk have led to campaigns regarding safe maternal sleep position. This study profiles the distribution of sleep positions overnight and relationships to sleep onset position during pregnancy, and the relationships between supine sleep, sleep-disordered breathing (SDB), and pregnancy outcomes. Data from three prospective cohort studies evaluating SDB in healthy and complicated pregnancies were pooled. All participants underwent one night of polysomnography in late pregnancy and birth outcome data were collected. 187 women underwent polysomnography at a median gestation of 34 weeks'. The left lateral position was preferred for falling asleep (52%) compared to supine (14%), but sleep onset position was the dominant sleep position overnight in only half (54%) of women. The median percentage of sleep time in the supine position was 24.2%; women who fell asleep supine spent more time supine overnight compared to those who began non-supine (48.0% (30.0,65.9) vs. 22.6% (5.7,32.2), p < .001). Women with growth-restricted fetuses were more likely to fall asleep supine than those with well-grown fetuses (36.6% vs. 7.5%, p < .001). Positional SDB was observed in 46% of those with an RDI ≥ 5. Sleep onset position was the dominant position overnight for half of the sample, suggesting that sleep onset position is not always a reliable indicator of body position overnight. Supine sleep was related to fetal growth restriction and birthweight at delivery, though causality cannot be inferred. It is critical that we pursue research into verifying the important relationship between supine sleep and increased stillbirth risk, and the mechanisms behind it.

Wallace, Meredith L; Lee, Soomi; Stone, Katie L; Hall, Martica H; Smagula, Stephen F; Redline, Susan; Ensrud, Kristine; Ancoli-Israel, Sonia; Buysse, Daniel J

doi: 10.1093/sleep/zsac015pmid: 35037946

Study ObjectivesTo identify actigraphy sleep health profiles in older men (Osteoporotic Fractures in Men Study; N = 2640) and women (Study of Osteoporotic Fractures; N = 2430), and to determine whether profile predicts mortality.MethodsWe applied a novel and flexible clustering approach (Multiple Coalesced Generalized Hyperbolic mixture modeling) to identify sleep health profiles based on actigraphy midpoint timing, midpoint variability, sleep interval length, maintenance, and napping/inactivity. Adjusted Cox models were used to determine whether profile predicts time to all-cause mortality.ResultsWe identified similar profiles in men and women: High Sleep Propensity [HSP] (20% of women; 39% of men; high napping and high maintenance); Adequate Sleep [AS] (74% of women; 31% of men; typical actigraphy levels); and Inadequate Sleep [IS] (6% of women; 30% of men; low maintenance and late/variable midpoint). In women, IS was associated with increased mortality risk (Hazard Ratio [HR] = 1.59 for IS vs. AS; 1.75 for IS vs. HSP). In men, AS and IS were associated with increased mortality risk (1.19 for IS vs. HSP; 1.22 for AS vs. HSP).ConclusionsThese findings suggest several considerations for sleep-related interventions in older adults. Low maintenance with late/variable midpoint is associated with increased mortality risk and may constitute a specific target for sleep health interventions. High napping/inactivity co-occurs with high sleep maintenance in some older adults. Although high napping/inactivity is typically considered a risk factor for deleterious health outcomes, our findings suggest that it may not increase risk when it occurs in combination with high sleep maintenance.

Adra, Noor; Sun, Haoqi; Ganglberger, Wolfgang; Ye, Elissa M; Dümmer, Lisa W; Tesh, Ryan A; Westmeijer, Mike; Cardoso, Madalena Da Silva; Kitchener, Erin; Ouyang, An; Salinas, Joel; Rosand, Jonathan; Cash, Sydney S; Thomas, Robert J; Westover, M Brandon

Pamidi, Sushmita; Kalyani, Rita R; Pien, Grace W

doi: 10.1093/sleep/zsac014pmid: 35137233

In the past decade, published literature has demonstrated the important relationship of sleep-disordered breathing (SDB) to the development of gestational diabetes mellitus (GDM) in late pregnancy. The prevalence estimates for GDM range between 10% and 25% of pregnancies in different regions worldwide [1]. GDM is defined as diabetes that is diagnosed for the first time during pregnancy, usually in the second or third trimester (24–28 weeks) based on a screening oral glucose tolerance test, in women without known pregestational diabetes. Women with GDM have a greater risk of birth complications, including spontaneous abortion, fetal anomalies, macrosomia, higher rates of cesarian section, and a 10-fold increased risk of developing type 2 diabetes later in life compared to women without GDM. Offspring of mothers with GDM also have an increased risk of developing obesity and type 2 diabetes [2, 3]. Several studies have shown an increased likelihood of GDM [4–8] among women with SDB compared to controls, even after adjusting for obesity. Nevertheless, data establishing how the timing of exposure to SDB influences the risk of developing GDM in late pregnancy is surprisingly sparse. The nuMoM2b study, a prospective cohort study of more than 3700 pregnant women, assessed SDB using home sleep apnea testing (HSAT) and demonstrated significant exposure–response relationships between the apnea–hypopnea index (AHI) and the secondary outcome of GDM development [4]. The odds for GDM in late pregnancy were observed to increase more than 3-fold among women who were found to have SDB during early pregnancy (median time at testing was 12 4/7 weeks of gestation) compared to those without SDB. Assessment of SDB was performed at least 1 week prior to glucose testing, helping to establish the biologic plausibility of SDB as a risk factor for GDM. SDB was reassessed in mid-pregnancy (~28 2/7 weeks of gestation), however, the temporality of the SDB–GDM relationship in mid-pregnancy is less well established. Other data include two retrospective studies that used population-based datasets and birth records to examine the relationship between maternal SDB and GDM [9, 10]. These analyses, however, did not distinguish between antenatal and pre-conception obstructive sleep apnea (OSA). Previous studies [4, 6, 9–11] also did not measure insulin resistance among individuals with SDB during early pregnancy. However, worsening severity of SDB detected in mid- to late pregnancy was associated with increased nocturnal and early morning glucose levels in women with GDM [11], adding to the literature on how SDB affects glucose metabolism during pregnancy. In this issue of the Journal, Sanapo and colleagues [12] performed a cross-sectional analysis of data from 2 ongoing studies and reported on the association between SDB in early pregnancy and insulin resistance and fasting glucose levels among 192 overweight or obese women (mean BMI of 35.1 kg/m2) without known pregestational diabetes. Women completed HSAT at a mean of 11.1 gestational weeks. They underwent modified homeostatic model assessment for insulin resistance (HOMA-IR using fasting C-peptide to replace insulin) at ~14–16 weeks of gestation; using this methodology, HOMA-IR was correlated with insulin sensitivity measured by oral glucose tolerance testing in pregnant women enrolled in the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study [13]. The authors found a linear relationship between respiratory event index (REI) and HOMA-IR after adjustment for demographics, parity, and gestational age (β = 0.25 ± 0.025; p = .003) that was attenuated after adjustment for BMI (β = 0.17 ± 0.026; p = .051). A similar relationship between oxygen desaturation index (ODI) and HOMA-IR remained significant in the fully adjusted model (β = 0.31 ± 0.024; p = .001). Although the presence of OSA (REI ≥5 events/hr) was not significantly associated with pancreatic β-cell function as estimated by the modified HOMA of β-cell function (HOMA-%β using C-peptide), the findings did demonstrate higher fasting glucose and higher fasting C-peptide levels among women with SDB in early pregnancy. What are the implications of these findings? Measurements of insulin resistance during early pregnancy are relevant for predicting maternal GDM risk. In a normal pregnancy, insulin resistance progressively increases during pregnancy until term to facilitate glucose transport across the placenta for fetal growth. Women with higher degrees of insulin resistance are at risk of developing GDM. During first-trimester glucose screening, impaired fasting glucose levels and/or an A1C level slightly above normal may indicate a higher risk for GDM and need for insulin during pregnancy [2]. Furthermore, results from the HAPO study have demonstrated that even mildly elevated glucose levels may be harmful for maternal–fetal health [14]. Thus, identifying risk factors for abnormal glucose metabolism during early pregnancy is an important clinical and research goal [15] that may yield novel treatments. The findings of the Sanapo study are relevant in that SDB in early pregnancy is associated with insulin resistance biomarkers that are likely to signify an elevated risk of developing GDM later in pregnancy. In the Sanapo study, women with OSA (vs. no OSA) were older, more obese, and had a higher likelihood of being multipara [12], similar to prior studies [4, 16, 17]. It is possible that some women in the Sanapo study had SDB prior to conception. However, without robust data on pre-conception SDB, it is impossible to examine whether antenatal SDB differentially impacts glucose metabolism and risk of GDM, in comparison to pre-conception SDB. While the ODI (mean 16 ± 12 events/hr) had a stronger association with HOMA-IR compared to REI (mean 7.7 ± 6.8 events/hr; p = .001 vs. p = .051, respectively), the desaturations were not all associated with respiratory events, and therefore the relevance of these findings need further exploration. Furthermore, several studies indicate that SDB in pregnancy is characterized predominantly by milder respiratory events, such as hypopneas with arousals and flow limitation, rather than by apneas and hypopneas with desaturation [4, 5, 11, 16–20]. Thus, the overall prevalence and clinical significance of respiratory events with desaturation in pregnancy are not yet well understood. Since limited HSAT rather than full polysomnography was used in the Sanapo study [12], it is unknown if REM-related SDB may have driven some of the relationships between SDB and metabolic dysfunction, as has been shown in prior studies [6, 11]. Furthermore, this was a cross-sectional study in which only fasting measures of glucose and C-peptide were available to assess insulin resistance and beta cell function. Women with normal or low BMI were also not included in this study. To date, despite the management of GDM with lifestyle behavior change and/or antihyperglycemic drug therapy as needed [2], the prevalence of GDM has been increasing steadily over the past several years [21, 22]. Thus, additional novel interventions are needed to optimize the prevention of GDM. While preliminary data from interventional studies have shown improvement in nocturnal glucose levels [23] and insulin secretion among women with GDM adherent to continuous positive airway pressure (CPAP) [24], larger studies are needed. This new work from Sanapo and colleagues a compelling rationale for future interventional studies that target the treatment of SDB earlier on in the pregnancy to improve glucose metabolism during early gestation and potentially prevent the development of GDM later in pregnancy. In turn, such interventions may decrease the cascade of future cardiometabolic risk for both mother and child. However, screening, diagnosing, and treating SDB during the limited duration of pregnancy pose substantial practical challenges for the treating physician. Future studies on pragmatic care pathways and optimizing CPAP adherence will be ultimately needed to translate research findings into clinical practice. Disclosure Statement The authors do not have any disclosures. 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Prevalence and changes in preexisting diabetes and gestational diabetes among women who had a live birth—United States, 2012-2016 . MMWR Morb Mortal Wkly Rep. 2018 ; 67 ( 43 ): 1201 – 1207 . doi:10.15585/mmwr.mm6743a2 Google Scholar Crossref Search ADS PubMed WorldCat 22. Getahun D , et al. Gestational diabetes in the United States: temporal trends 1989 through 2004 . Am J Obstet Gynecol . 2008 ; 198 ( 5 ): 525.e1 – 525.e5 . Google Scholar Crossref Search ADS WorldCat 23. Duong A , et al. CPAP treatment reduces nocturnal glucose levels in gestational diabetes: a pilot randomized-controlled trial (RCT). Presented at: American Thoracic Society 2020—A97. SRN: New Insights into the Cardiometabolic Consequences of Insufficient Sleep . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC 24. Chirakalwasan N , et al. Continuous positive airway pressure therapy in gestational diabetes with obstructive sleep apnea: a randomized controlled trial . J Clin Sleep Med. 2018 ; 14 ( 3 ): 327 – 336 . doi:10.5664/jcsm.6972 Google Scholar Crossref Search ADS PubMed WorldCat © The Author(s) 2022. Published by Oxford University Press on behalf of Sleep Research Society. All rights reserved. For permissions, please e-mail: [email protected] This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Baird, Benjamin; Tononi, Giulio; LaBerge, Stephen

doi: 10.1093/sleep/zsab294pmid: 35934510

Study Objectives(1) To critically test whether a previously reported increase in frontolateral 40 Hz power in lucid REM sleep, used to justify the claim that lucid dreaming is a “hybrid state” mixing sleep and wakefulness, is attributable to the saccadic spike potential (SP) artifact as a corollary of heightened REM density. (2) To replicate the finding that lucid dreams are associated with physiological activation, including heightened eye movement density, during REM sleep. (3) To conduct an exploratory analysis of changes in EEG features during lucid REM sleepMethodsWe analyzed 14 signal-verified lucid dreams (SVLDs) and baseline REM sleep segments from the same REM periods from six participants derived from the Stanford SVLD database. Participants marked lucidity onset with standard left-right-left-right-center (LR2c) eye-movement signals in polysomnography recordings.ResultsCompared to baseline REM sleep, lucid REM sleep had higher REM density (β = 0.85, p = 0.002). Bayesian analysis supported the null hypothesis of no differences in frontolateral 40 Hz power after removal of the SP artifact (BH = 0.18) and ICA correction (BH = 0.01). Compared to the entire REM sleep period, lucid REM sleep showed small reductions in low-frequency and beta band spectral power as well as increased signal complexity (all p < 0.05), which were within the normal variance of baseline REM sleep.ConclusionsLucid dreams are associated with higher-than-average levels of physiological activation during REM sleep, including measures of both subcortical and cortical activation. Increases in 40 Hz power in periorbital channels reflect saccadic and microsaccadic SPs as a result of higher REM density accompanying heightened activation.

Strauss, Mélanie; Griffon, Lucie; Van Beers, Pascal; Elbaz, Maxime; Bouziotis, Jason; Sauvet, Fabien; Chennaoui, Mounir; Léger, Damien; Peigneux, Philippe

doi: 10.1093/sleep/zsac022pmid: 35037060

Sleep is known to benefit memory consolidation, but little is known about the contribution of sleep stages within the sleep cycle. The sequential hypothesis proposes that memories are first replayed during nonrapid-eye-movement (NREM or N) sleep and then integrated into existing networks during rapid-eye-movement (REM or R) sleep, two successive critical steps for memory consolidation. However, it lacks experimental evidence as N always precedes R sleep in physiological conditions. We tested this sequential hypothesis in patients with central hypersomnolence disorder, including patients with narcolepsy who present the unique, anti-physiological peculiarity of frequently falling asleep in R sleep before entering N sleep. Patients performed a visual perceptual learning task before and after daytime naps stopped after one sleep cycle, starting in N or R sleep and followed by the other stage (i.e. N-R vs. R-N sleep sequence). We compared over-nap changes in performance, reflecting memory consolidation, depending on the sleep sequence during the nap. Thirty-six patients who slept for a total of 67 naps were included in the analysis. Results show that sleep spindles are associated with memory consolidation only when N is followed by R sleep, that is in physiologically ordered N-R naps, thus providing support to the sequential hypothesis in humans. In addition, we found a negative effect of rapid-eye-movements in R sleep on perceptual consolidation, highlighting the complex role of sleep stages in the balance to remember and to forget.

Liu, Wei K; Dye, Thomas J; Horn, Paul; Patterson, Connor; Garner, David; Simakajornboon, Narong

doi: 10.1093/sleep/zsac005pmid: 35022768

Restless sleep disorder (RSD) is a newly defined sleep-related movement disorder characterized by large muscle movements (LMM) in sleep. We examined the sleep study, clinical characteristics, and daytime functioning in children with RSD and compared them to children with periodic limb movement disorder (PLMD) or restless legs syndrome (RLS). Video polysomnography from 47 children with restless sleep was retrospectively reviewed for LMM and age- and sex-matched to 34 children with PLMD and 12 children with RLS. Data examined included PSG characteristics, ferritin, Pediatric Quality of Life (PedsQL), and Epworth Sleepiness Scale (ESS). Fourteen children met the clinical criteria for RSD with an LMM index of 5 or more per hour of sleep. Mean ESS was elevated in patients with RSD compared to either the PLMD or RLS groups though the result did not reach statistical significance (RSD = 10.20 ± 6.81, PLMD = 6.19 ± 4.14, RLS = 6.25 ± 4.90). The PedsQL score was significantly decreased in the RLS group compared to RSD and was reduced overall in all three groups (PedsQL Total RSD = 70.76 ± 18.05, PLMD = 57.05 ± 20.33, RLS = 53.24 ± 16.97). Serum ferritin values were similar in all three groups (RSD = 26.89 ± 10.29, PLMD = 33.91 ± 20.31, RLS = 23.69 ± 12.94 ng/mL, p = ns). Children with RSD demonstrate increased daytime sleepiness compared to PLMD or RLS and all three disease groups showed decreased quality of life. Further studies are needed to examine long-term consequences of RSD.