Nocturnal Sleep Latency Research Articles

Persian version of brief infant sleep questionnaire (BISQ): a psychometric evaluation

BackgroundThe high prevalence of sleep problems and their negative consequences on children and parents highlight the need to design early screening instruments to evaluate sleep problems in early childhood. We aimed to determine the validity and reliability of the Brief Infant Sleep Questionnaire (BISQ) among the Iranian population.Methods and materialsThis study included 646 one-year-old infants by random sampling from the PERSIAN birth cohort study. Following the forward-backward translation of the BISQ, its psychometric properties, including construct validity in terms of concurrent and convergent validities as well as reliability, were evaluated.ResultsThe CVIs and CVR ranged between 0.8 and 1.00 for all items. Therefore, we keep all the items of the original version of the BISQ in the Persian BISQ. Concurrent validity was assessed by comparing items of the Persian BISQ among different maternal views regarding their infant’s sleep. All BISQ items were significantly different among the two levels of maternal view about the infant’s sleep problem except daytime sleep duration. The convergent validity of the BISQ was evaluated by calculating the correlation between BISQ items and the ISQ (infant sleep questionnaire) total score as a similar tool. ISQ score was adequately correlated with nocturnal sleep latency and the number of waking at night (rs ranged from 0.59 to 0.72). In addition, the associations of mothers’ and infants’ demographic variables and nutritional and gestational variables with BISQ items were presented to confirm construct validity. Strong correlations were found between the repeated sleep measures for sleep arrangement, sleep position, and sleep situation (kappa ranged from 0.65 to 0.84), nocturnal sleep duration, daytime sleep duration number of wakings at night, night waking duration, nocturnal sleep latency and sleep-onset time (ICC ranged 0.91 to 0.99).ConclusionThe Persian version of the BISQ is a reliable and valid measure for assessing sleep problems in infants. It would be helpful to be utilized for the early diagnosis of infants’ sleep problems.

Changes in Sleep Pattern During the COVID-19 Lockdown in Patients With Narcolepsy, Idiopathic Hypersomnia, and Restless Legs Syndrome.

To explore the first coronavirus disease 2019 (COVID-19) lockdown effect on sleep symptoms in patients with narcolepsy, idiopathic hypersomnia (IH), and restless legs syndrome (RLS). Between March and May 2020, a sample of adult patients regularly followed up in a Reference Hospital Sleep Unit (299 with narcolepsy, 260 with IH, and 254 with RLS) was offered an online survey assessing their sleep-wake habits, daily activities, medication intake, and validated scales: International RLS Study Group questionnaire, Narcolepsy Severity Scale (NSS), IH Severity Scale (IHSS), Epworth Sleepiness Scale (ESS), Insomnia Severity Index, Beck Depression Inventory-II, and European Quality of Life (QoL) scale. The survey was proposed once, and the questions were answered for the prelockdown (recall of the month before the confinement) and the lockdown (time of study) periods. Overall, 331 patients completed the survey (response rate 40.7%): 102 with narcolepsy, 81 with IH, and 148 with RLS. All patients reported later bedtimes, with reduced differences for time in bed (TIB) and total sleep time (TST) over 24 hours between weekdays and weekends. Patients with narcolepsy spent more TIB and increased TST overnight, with more daytime napping. They had more awakenings, higher ESS scores, lower QoL, and no NSS changes. Patients with IH also increased their TIB, TST overnight and 24 hours on weekdays. Nocturnal sleep latency and the number of awakenings increased but with no change in ESS, QoL, and IHSS scores. Patients with RLS reported longer nocturnal sleep latency, more awakenings, more naps, decreased TIB, and TST overnight. RLS severity increased while QoL decreased. A significant portion of patients reported disease worsening during the lockdown (narcolepsy: 39.4%, IH: 43.6%, and RLS: 32.8%), and some patients stopped or lowered their medication (narcolepsy: 22.5%, IH: 28%, and RLS: 9.5%). During the lockdown, all patients reported later bedtimes; those with narcolepsy and IH extended their sleep duration unlike patients with RLS. These changes were often associated with negative consequences on QoL. In the current context of recurrent COVID-19 waves, the recent development of teleconsultations should enable physicians to monitor patients with chronic sleep disorders more closely and to recommend optimized sleep schedules and duration, in order to prevent psychological problems and improve their QoL.

Clinical and polysomnographic course of childhood narcolepsy with cataplexy

Our aim was to investigate the natural evolution of cataplexy and polysomnographic features in untreated children with narcolepsy with cataplexy. To this end, clinical, polysomnographic, and cataplexy-video assessments were performed at diagnosis (mean age of 10 ± 3 and disease duration of 1 ± 1 years) and after a median follow-up of 3 years from symptom onset (mean age of 12 ± 4 years) in 21 children with narcolepsy with cataplexy and hypocretin 1 deficiency (tested in 19 subjects). Video assessment was also performed in two control groups matched for age and sex at first evaluation and follow-up and was blindly scored for presence of hypotonic (negative) and active movements. Patients’ data at diagnosis and at follow-up were contrasted, compared with controls, and related with age and disease duration. At diagnosis children with narcolepsy with cataplexy showed an increase of sleep time during the 24 h; at follow-up sleep time and nocturnal sleep latency shortened, in the absence of other polysomnographic or clinical (including body mass index) changes. Hypotonic phenomena and selected facial movements decreased over time and, tested against disease duration and age, appeared as age-dependent. At onset, childhood narcolepsy with cataplexy is characterized by an abrupt increase of total sleep over the 24 h, generalized hypotonia and motor overactivity. With time, the picture of cataplexy evolves into classic presentation (i.e. brief muscle weakness episodes triggered by emotions), whereas total sleep time across the 24 h decreases, returning to more age-appropriate levels.

Comparative sensitivity of a simulated driving task to self-report, physiological, and other performance measures during prolonged wakefulness

Objectives The objectives of this study were to compare (1) the sensitivity of simulated driving to self-report measures, nocturnal sleep latency tests (SLTs), and an auditory vigilance task and (2) urban and motorway driving. Methods Healthy males 18 to 35 years maintained wakefulness for one night and were tested at 2400, 0230, 0500 and 0730 h. In Study 1 ( n=11), the SLTs were followed by auditory vigilance and simulated driving tasks; in Study 2 ( n=18), the SLTs were preceded and followed by simulated driving on motorway and urban routes. Results In Study 1, speed variability, tracking variability, and driving off the road on the driving simulator had comparable sensitivity to d′ on the auditory vigilance task. In Study 2, driving performance was consistently worse on the motorway route. Conclusion The driving simulator was equally sensitive to another performance measure during prolonged wakefulness and impairments were greater with motorway driving.

Daytime sleepiness in stable hemodialysis patients

Background: Patients frequently sleep during hemodialysis (HD), a behavior often attributed to treatment-related fatigue and/or simple boredom. The possibility that this behavior reflects a more pervasive underlying increase in daytime sleepiness has never been systematically examined. Thus, we studied a sample of HD patients on an off-dialysis day to establish the presence or absence of daytime sleepiness independent of effects of treatment, quantify its severity, and identify associated demographic, metabolic, and sleep-related variables. Methods: Forty-six stable HD patients underwent polysomnography, followed the next day (a nondialysis day) by the Multiple Sleep Latency Test (MSLT; low score = greater sleepiness), a measure of physiological daytime sleepiness. Subjects also completed the Epworth Sleepiness Scale (ESS; high score = greater sleepiness), a measure of subjective daytime sleepiness. Results: One third (n = 15) of subjects had MSLT scores suggesting abnormal levels of physiological daytime sleepiness, and six subjects had scores consistent with severe, pathological sleepiness. Thirty percent (n = 14) had significant subjective daytime sleepiness as measured by the ESS. However, MSLT and ESS scores were unrelated. Higher indices of sleep apnea (r = −0.324; P = 0.028) and brief arousals (r = −0.370; P = 0.009) correlated significantly with increased physiological, but not subjective, sleepiness. Longer nocturnal sleep latencies (r = 0.350; P = 0.017) and greater percentage of rapid-eye-movement sleep (r = 0.302; P = 0.042) were associated with decreased physiological sleepiness. Other major demographic, metabolic, and sleep-related variables did not correlate with MSLT scores, and none of the variables examined were related to ESS scores. Conclusion: Daytime sleepiness is common in HD patients and may be severe despite the absence of obvious clinical risk factors for the condition. Thus, research designed to identify cost-effective indicators of daytime sleepiness and evaluate the detrimental effects of sleepiness on clinical outcomes in HD patients is warranted. Am J Kidney Dis 41:394-402.

Nocturnal sleep, daytime sleepiness, and quality of life in stable patients on hemodialysis

BackgroundAlthough considerable progress has been made in the treatment of chronic kidney disease, compromised quality of life continues to be a significant problem for patients receiving hemodialysis (HD). However, in spite of the high prevalence of sleep complaints and disorders in this population, the relationship between these problems and quality of life remains to be well characterized. Thus, we studied a sample of stable HD patients to explore relationships between quality of life and both subjective and objective measures of nocturnal sleep and daytime sleepinessMethodsThe sample included forty-six HD patients, 24 men and 22 women, with a mean age of 51.6 (10.8) years. Subjects underwent one night of polysomnography followed the next morning by a Multiple Sleep Latency Test (MSLT), an objective measure of daytime sleepiness. Subjects also completed: 1) a brief nocturnal sleep questionnaire; 2) the Epworth Sleepiness Scale; and, 3) the Quality of Life Index (QLI, Dialysis Version) which provides an overall QLI score and four subscale scores for Health & Functioning (H&F), Social & Economic (S&E), Psychological & Spiritual (P&S), and Family (F). (The range of scores is 0 to 30 with higher scores indicating better quality of life.)ResultsThe mean (standard deviation; SD) of the overall QLI was 22.8 (4.0). The mean (SD) of the four subscales were as follows: H&F – 21.1 (4.7); S&E – 22.0 (4.8); P&S – 24.5 (4.4); and, F – 26.8 (3.5). H&F (rs = -0.326, p = 0.013) and F (rs = -0.248, p = 0.048) subscale scores were negatively correlated with periodic limb movement index but not other polysomnographic measures. The H&F subscale score were positively correlated with nocturnal sleep latency (rs = 0.248, p = 0.048) while the H&F (rs = 0.278, p = 0.030) and total QLI (rs = 0.263, p = 0.038) scores were positively associated with MSLT scores. Both of these latter findings indicate that higher life quality is associated with lower sleepiness levels. ESS scores were unrelated to overall QLI scores or the subscale scores. Subjective reports of difficulty falling asleep and waking up too early were significantly correlated with all four subscale scores and overall QLI. Feeling rested in the morning was positively associated with S&E, P&S, and Total QLI scores.ConclusionSelected measures of both poor nocturnal sleep and increased daytime sleepiness are associated with decreased quality of life in HD patients, underscoring the importance of recognizing and treating these patients' sleep problems.

Self-reported levels of sleepiness among subjects with insomnia

Objectives: To determine the prevalence of sleepiness in a cohort of insomnia subjects. We evaluated if differential levels of subjective sleepiness predict systematic differences in the polysomnographic characteristics of these subjects. Background: Insomnia is prevalent among the adult population. While it has been speculated that sleepiness may be an important daytime consequence of insomnia, this has not been demonstrated. Methods: Sixty-two subjects with complaints of insomnia for at least 6 months were polysomnographically evaluated. Subjects were asked to self-report their level of sleepiness based on their experiences for the previous 7 days. Subjects were divided into three groups based on their level of sleepiness. Sleepiness was determined using the excessive daytime sleepiness scale of the Sleep/Wake Activity Inventory (SWAI-EDS). Results: Twenty-two percent of insomnia subjects were found to be sleepy on the EDS scale of the SWAI. The level of sleepiness was also found to predict difficulty initiating sleep both on the nocturnal scale of the SWAI, and on nocturnal polysomnography. Conclusions: This study established a base rate of sleepiness among a cohort of insomnia subjects. It also demonstrated a wide spectrum of sleepiness/alertness among subjects with insomnia. Differential levels of sleepiness were found to predict nocturnal sleep latencies.

Repeated nocturnal sleep latencies in narcoleptic, sleepy and alert subjects

Objectives: The purpose of this study was to assess nocturnal sleep latencies among narcoleptics.Methods: Thirteen narcoleptics and matched sleepy and alert controls participated in this study. Subjects were awakened three times on each of two experimental nights. The latencies to sleep and rapid eye movement sleep were evaluated at the beginning of the night and following each experimental awakening.Results: The alert group (AG) had a significantly longer mean nocturnal sleep latency than the narcoleptic (NG) and sleepy groups (SG). The sleep latencies at 23:00 and 01:10 h were significantly longer than the latencies at 03:10 and 05:10 h. The interaction between group and time of night demonstrated longer latencies at 23:00 and 03:10 h for the AG when compared to the SG and the NG. At 01:10 and 05:10 h all groups had comparable latencies. The number of subjects in the NG who had multiple sleep onset REM periods (SOREMPs) was significantly higher than in either the AG or the SG.Conclusions: Narcoleptics were found to have a heightened propensity to fall asleep and increased number of SOREMPs during nocturnal sleep opportunities. These characteristics are consistent with the daytime polysomnographic findings known in this patient population.

Nocturnal sleep latencies among alert, alert-deprived and sleepy subjects

Twenty-seven healthy, asymptomatic subjects participated in a study to determine repeated nocturnal sleep latencies as a function of level of daytime sleepiness. Subjects were screened polysomnographically and were determined to be free of any sleep pathology. Nine subjects had a screening multiple sleep latency test (MSLT) of ≤5 min and 18 had a MSLT of ≥10 min. Subjects were assigned to 3 groups, sleepy (MSLT ≤ 5 min), alert, and alert sleep-deprived groups (MSLT ≥ 10 min). Repeated nocturnal latencies to sleep were determined at 2300, 0110, 0310 and 0510 h on 2 nights with at least 5 days between nights. The results showed a main effect of group on the repeated nocturnal sleep latencies. Post-hoc tests demonstrated longer repeated nocturnal latencies among alert subjects compared to the sleepy and alert sleep-deprived subjects. The latter two groups had comparable sleep latencies. A significant main effect of time of night was also shown. The 0510 h latency was significantly shorter than the latencies at 2300 and 0110 h. The 0310 h latency was significantly shorter than the 0110 h latency and comparable to the 2300 and 0510 h latency. Significant correlations were found between daytime MSLT, repeated nocturnal sleep latencies, and nocturnal sleep time. These results show systematic differences in repeated nocturnal sleep latencies among sleepy and alert subjects and extend the already described characteristics of these subjects by comparing them to a group of alert sleep-deprived subjects.

The Relationship of Sleepiness and Blood Pressure to Respiratory Variables in Obstructive Sleep Apnea

As a follow-up to a previous assessment of complications of sleep-disturbed breathing in 265 patients, we have reevaluated measures of sleepiness and hypertension in patients with obstructive sleep apnea (OSA) (n = 518), central sleep apnea (n = 50), and subclinical sleep-disordered breathing (SDB) (n = 107). Both subjective and objective (multiple sleep latency test [MSLT]) measures indicated that OSA patients were sleepier than those with subclinical SDB. The OSA patients weighed significantly more than the patients with central sleep apnea or subclinical SDB. They had a higher proportion of men, described more habitual sleepiness, and had a higher likelihood of feeling unrefreshed in the morning compared with the group with subclinical SDB. Among the OSA patients, there was a significant correlation between subjective and objective assessment of sleepiness, but this relationship was quantitatively very small. A forward stepwise regression analysis revealed that weight, and to a lesser degree waking time after sleep onset, could account for 65.5% of the variance in subjective sleepiness. Seventy-five percent of the variance of the mean sleep latency in the MSLT could be accounted for by the mean minimum arterial oxygen saturation in non-REM sleep and the nocturnal sleep latency. Diastolic BP was significantly higher in OSA patients compared with the patients with central sleep apnea and subclinical SDB. When covarying for weight, age, and gender, this effect lost significance. Among OSA patients taken by themselves, 98.3% of the variance in diastolic blood pressure could be accounted for by the mean minimum arterial oxygen saturation in non-REM sleep, with very small additional contributions of apnea/hypopnea index, weight, and age. In summary, among patients across a spectrum of SDB, differences in diastolic BP were primarily associated with weight, age, and gender. Among OSA patients, perhaps because of a more limited variance in weight, diastolic BP was associated with measures of SDB.

Patterns of sleep and wakefulness in treated narcoleptic subjects.

In most reported studies of treatment for narcolepsy, the efficacy of treatment has been assessed in the sleep laboratory, but not in the natural work and home settings. We therefore assessed the sleep/wake patterns of 25 subjects with narcolepsy, whose symptoms were considered under satisfactory control by the subjects and their physicians, using polygraphic recorders, and compared these with the patterns of 25 control subjects matched for age and gender. Data from one matched pair of subjects were excluded for technical reasons. There was no difference between the two groups of subjects in the total amount of sleep obtained during the 24-hour monitoring period. Narcoleptic subjects had shorter nocturnal sleep latencies and more disrupted nocturnal sleep than control subjects. Despite taking their usual medications, narcoleptic subjects averaged 44 minutes of daytime sleep compared to 4.8 minutes for controls. There was wide variation in the amount of daytime sleep among narcoleptics: 10 subjects did not sleep during the day, whereas the other 14 averaged 2.7 naps per day for an average of 76.2 minutes of daytime sleep. These findings indicate that daytime sleep episodes were common in narcoleptic patients who considered their treatment satisfactory. Wide variations in the amount of daytime sleep may reflect differences in disease severity, responsiveness to medications or willingness to tolerate daytime sleep episodes.

The 24-hour sleep propensity function: experimental bases for somnotypology.

The present study investigated the temporal structure of sleep propensity during 48 hours using an ultrashort 7-min sleep/13-min wake cycle. Eight subjects were tested under two experimental conditions of either attempting sleep, or resisting sleep after a monitored night in the laboratory. Electrophysiological recordings were carried out during the 7-min trials. The temporal structure and the overall level of sleepiness of the 48-hour sleep propensity functions calculated from the amount of total sleep in each trial revealed a high within-subjects stability. This was found both across the two days of the study within conditions, and across conditions. Also, diurnal levels of sleepiness were systematically related to nocturnal sleep parameters. Subjects having short nocturnal sleep latencies and higher sleep efficiencies slept more during the day. It is proposed that the structure and level of the sleep propensity function can be used to characterize individuals along two dimensions of somnotypology: "morningness-eveningness" and "sleepy-alert."