Wrist actigraphy in insomnia.

To assess the use of actigraphy in evaluating insomnia, 36 patients with a serious complaint of insomnia slept 3 nights each in the laboratory, where the usual polysomnograms (PSGs) were obtained as well as actigraphic assessments of their sleep. Patients also wore actigraphs for 7 days at home, were extensively interviewed and filled out psychometric tests. Based on all this information, the patients were then diagnosed according to the International Classification of Sleep Disorders. Averaged over the 3 nights for each insomniac, the mean discrepancy between actigram and PSG was 49 minutes per night. In three-fourths of the cases, actigram and PSG agreed to within 1 hour on the total amount of sleep per night. Discrepancies, however, were not random: In patients with psychophysiologic insomnia and in insomnia associated with psychiatric disease, the actigram typically overestimated sleep when compared with the PSG. In patients with sleep-state misperception, the actigram was either quite accurate or it underestimated sleep when compared with the PSG. Comparing laboratory with home sleep, one-third of all insomniacs slept better in the laboratory and two-thirds slept better at home. In addition, night-by-night variability was higher at home than in the laboratory. Based on our study, we now recommend actigraphy as an additional tool in the clinical evaluation of insomnia, but we believe that in complex cases it should be combined with 1 PSG night in the sleep disorders center.     

Maintenance of wakefulness test as a predictor of driving performance in patients with untreated obstructive sleep apnea

STUDY OBJECTIVE: To determine the ability of Maintenance of Wakefulness Test (MWT) to predict simulated driving performance in patients suffering from sleep apnea syndrome. DESIGN: Study involving one hour of simulated driving, one night of polysomnography (PSG), and a 4 x 40-minute MWT. SETTING: Sleep laboratory. PATIENTS: Thirty male patients with untreated obstructive sleep apnea syndrome (OSAS) (mean age [+/- SD] = 51 +/- 8 years, range 34-62; mean body mass index (BMI) [+/- SD] = 29 +/- 3, range 24-37; mean apnea/hypopnea index (AHI) [+/- SD] = 43 +/- 24, range 14-96). As defined by MWT mean sleep latency, 23.3% of the patients were sleepy (0-19 min), 33.3% were alert (20-33 min), and 43.4% were fully alert (34-40 min). MEASUREMENTS: Nocturnal PSG, mean sleep latency at 4 x 40-minute MWT trials, Epworth Sleepiness Scale (ESS), and standard deviation from the center of the road (SDS) on driving simulator. RESULTS: Mean MWT scores inversely correlated with SDS during the simulated driving session (Pearson's r = -0.513, P < 0.01). We found a significant effect of MWT groups (sleepy, alert, or fully alert) on SDS (ANOVA, F(2, 29) = 5.861, P < 0.01). Post hoc tests revealed that the sleepy group had a higher SDS than the fully alert group (P = 0.006). ESS, AHI, microarousal index, and total sleep time did not predict simulated driving performance. CONCLUSIONS: A pathological MWT mean sleep latency (0-19 min) is associated with simulated driving impairment. Before MWT can be used to predict the driving ability of untreated patients with OSAS, further studies are needed to confirm that pathological MWT scores are associated with real driving impairment.     

Daytime testing after laboratory or home-based polysomnography: comparisons of middle-aged insomnia sufferers and normal sleepers

Many studies have shown only modest differences between insomnia sufferers and matched, non-complaining normal controls in regard to their levels of daytime sleepiness and diurnal performances. The current study was conducted to determine whether such daytime comparisons might be affected by the setting (home vs. sleep lab) in which study participants sleep on the nights before such testing. The study used a counter-balanced, matched-group design in which participants underwent three consecutive nocturnal polysomnographs (PSG) conducted either in the sleep lab or in their homes prior to undergoing daytime multiple sleep latency test (MSLT) and computer-administered performance testing. The study participants were 35 (18 women and 17 men) middle-aged (40-59 years) non-complaining normal sleepers and 33 middle-aged insomnia sufferers (17 women and 16 men) who met structured interview criteria for persistent primary insomnia. Use of a hierarchical linear statistical model showed only insomnia sufferers who underwent nocturnal home PSG were more alert on the MSLT than were normal sleepers who underwent lab PSG. However, these insomnia sufferers showed a greater propensity toward attention lapses on selected reaction time tests than did either of the two normal control groups (i.e. either those who slept in the lab or those who slept at home). The results suggest the nocturnal sleep setting (home vs. lab) may affect subsequent MSLT and performance test comparisons of insomnia sufferers and normal sleepers.     

Relation between ambulatory actigraphy and laboratory polysomnography in insomnia practice and research

Actigraphy is increasingly used in practice and research studies because of its relative low cost and decreased subject burden. How multiple nights of at‐home actigraphy compare to one independent night of in‐laboratory polysomnography (PSG) has not been examined in people with insomnia. Using event markers (MARK) to set time in bed (TIB) compared to automatic program analysis (AUTO) has not been systematically evaluated. Subjects (n = 30) meeting DSM‐5 criteria for insomnia and in‐laboratory PSG sleep efficiency (SE) of <85% were studied. Subjects were free of psychiatric, sleep or circadian disorders, other chronic conditions and medications that effect sleep. Subjects had an in‐laboratory PSG, then were sent home for 7 nights with Philips Actiwatch Spectrum Plus. Data were analysed using Philips Actiware version 6. Using the mean of seven nights, TIB, total sleep time (TST), SE, sleep‐onset latency (SOL) and wake after sleep onset (WASO) were examined. Compared to PSG, AUTO showed longer TIB and TST and less WASO. MARK only differed from PSG with decreased WASO. Differences between the PSG night and the following night at home were found, with better sleep on the first night home. Actigraphy in people with insomnia over seven nights is a valid indicator of sleep compared to an independent in‐laboratory PSG. Event markers increased the validity of actigraphy, showing no difference in TIB, TST, SE and SOL. AUTO was representative of SE and SOL. Increased SE and TST without increased TIB suggests possible compensatory sleep the first at night home after in‐laboratory PSG.     

The effect of clustered versus regular sleep fragmentation on daytime function

Previously, we found that regular sleep fragmentation, similar to that found in patients with sleep apnoea/hypopnoea syndrome (SAHS), impairs daytime function. Apnoeas and hypopnoeas occur in groups in patients with REM or posture related SAHS. Thus, we hypothesised that clustered sleep fragmentation would have a similar impact on daytime function as regular sleep fragmentation. We studied 16 subjects over two pairs of 2 nights and 2 days. The first night of each pair was for acclimatisation. On the second night, subjects either had their sleep fragmented regularly every 90 s, or fragmented every 30 s for 30 min every 90 min, the remaining 60 min being undisturbed. We fragmented sleep with tones to produce a minimum 3 s increase in EEG frequency. During the days following each pair of nights we tested subjects daytime function. Total sleep time (TST) and microarousal frequency were similar no both study nights. We found significantly less stage 2 (55 SD 4, 62 +/- 7%; P = 0.001) and more slow wave sleep (21 SD 3, 12 +/- 6%; P < 0.001) on the clustered night. Mean sleep onset latency was similar on MSLT (clustered 10 SD 5, regular 9 +/- 4 min; P = 0.7) and MWT (clustered 32 SD 7, regular 30 +/- 7 min; P = 0.2). There was no difference in subjects mood or cognitive function after either study night. These results suggest that although there is more slow wave sleep (SWS) on the clustered night, similar numbers of sleep fragmenting events produced similar daytime function whether the events were evenly spaced or clustered.     

Polysomnography and self-reported sleep, pain, fatigue, and anxiety in children with active and inactive juvenile rheumatoid arthritis

OBJECTIVE: To compare polysomnography (PSG) and self-reported sleep, symptoms (pain and fatigue), and anxiety between children with active and inactive juvenile rheumatoid arthritis (JRA) and examine relations among sleep, symptoms, and anxiety. METHODS: Two consecutive nights of PSG, self-reported sleep, and symptoms were obtained in 70 children 6-11 years of age with active (n = 35) or inactive (n = 35) JRA. RESULTS: On the second (study) night, PSG and self-reported sleep variables were not different, but pain and fatigue were significantly higher (both p <.02) in children with active compared to inactive disease. In a stepwise regression, age, medications, disease status, anxiety, evening pain, total sleep time, and arousals explained 36% of the variance in fatigue and age, disease status, and evening pain were significant (all p <.04) predictors of fatigue. All children showed longer sleep latency and reduced sleep efficiency on the first night in the laboratory. CONCLUSIONS: Sleep was not altered in children with active JRA, however, the "first night effect" suggests that valid laboratory sleep assessments require an adaptation night.     

Toddler behavior following polysomnography: effects of unintended sleep disturbance

STUDY OBJECTIVES: Childhood sleep disorders are consistently shown to affect behavior and cognition, but first-night effects on these measures are generally unknown. We sought to examine how sleep in the home versus the laboratory differed among healthy toddlers and how such differences relate to standardized scores on assessments the morning following polysomnography. DESIGN, SETTING, AND PARTICIPANTS: Twenty healthy 14-month-olds wore actigraphs during nighttime sleep at home for 5 nights preceding and during standard overnight laboratory polysomnography. The Bayley Scales of Infant Development (BSID-II) were administered once the morning after polysomnography. MEASUREMENTS AND RESULTS: All subjects had normal polysomnography. Sleep-start times at home and during polysomnography did not differ, whereas, during polysomnography, subjects awoke earlier (p = .008, d = .58), their total sleep time (p <. 001, d = 1.1) and sleep efficiency (p = .004, d = .57) were reduced, and they had shorter sleep-bout lengths (p = .004, d = .03), less immobility (p = .003, d = .62), and greater average activity during sleep (p <. 001, d = .98). Standardized assessments were not affected by differences between home and polysomnography night sleep, but children with greater emotional regulation difficulty had a lower percentage of immobility (r = -0.67, p = .001) and increased sleep fragmentation (r = -0.60, p = .005) during polysomnography. CONCLUSIONS: Although sleep-onset times were preserved, sleep in the laboratory was disrupted, compared with at home. These differences did not affect standardized scores, but the magnitude of the difference was associated with worse emotional regulation. The effects of sleep disturbance during polysomnography, or the influence of poor emotional regulation on sleep in the laboratory, should be considered in studies of young children.     

The influence of polysomnography on the Multiple Sleep Latency Test and other measures of daytime sleepiness

INTRODUCTION: According to its guidelines, the Multiple Sleep Latency Test (MSLT) should be performed following an all-night polysomnography (PSG). However, the sleep quality and consequently the MSLT results may be affected by PSG and by the fact that a subject sleeps under unfamiliar conditions. The aim of this study was to examine whether PSG performed in a sleep laboratory has any influence on the MSLT and other measures of daytime sleepiness. METHODS: Twenty healthy subjects with a mean age of 35.9+/-10.1 years underwent two MSLT examinations, and the 2 examination days were at least 4 weeks apart. In addition, on each occasion a monotonous vigilance task (VT) was performed and the subjects were asked to fill out the Epworth Sleepiness (ESS) and Visual Analogue Scales (VAS). In a cross-over design, a group of 10 subjects underwent a MSLT (MSLT-P) following a PSG and, on a second occasion, a MSLT (MSLT-N) was performed without a prior PSG. Vice versa, a second group of 10 subjects underwent first MSLT-N and then MSLT-P. RESULTS: None of the MSLT parameters differed significantly between MSLT-P and MSLT-N. The other measures of daytime sleepiness (VT, ESS, VAS) also showed no evidence of significant differences between days with and without a prior PSG. CONCLUSIONS: The results of MSLT and other measures of daytime sleepiness in healthy subjects are not influenced by the fact whether or not the subjects had a PSG the night prior to MSLT.     

Test-retest reliability of the MSLT

The test-retest reliability of the Multiple Sleep Latency Test (MSLT) was evaluated in 14 healthy normal subjects. Each slept a single night in the laboratory (8 h time in bed) and received the MSLT the following day (1000, 1200, 1400, and 1600 h) on two occasions separated by 4-14 months. Mean sleep latency (four tests) was highly reliable from MSLT to MSLT (r = 0.97, p less than 0.001). The test-retest reliability did not change as a function of the interval of time between tests or as a function of the level of sleepiness (range = 4-20 min) within the population. However, as the number of tests comprising the MSLT was reduced below three, the reliability was reduced such that only 50% or less of the variance could be predicted.     

Using a wrist-worn device based on peripheral arterial tonometry to diagnose obstructive sleep apnea: in-laboratory and ambulatory validation

STUDY OBJECTIVES: To assess the accuracy of a wrist-worn device (Watch_PAT 100) to diagnose obstructive sleep apnea in the home. DESIGN: Participants completed 2 overnight diagnostic studies with the test device: 1 night in the laboratory with concurrent polysomnography and 1 night in the home with only the Watch_PAT. The order of the laboratory and home study nights was random. The frequency of respiratory events on the PSG was quantified using indexes based on 2 definitions of hypopnea: the respiratory disturbance index (RDI) using American Academy of Sleep Medicine Task Force criteria for clinical research, also referred to as the Chicago criteria (RDI.C), and the Medicare guidelines (RDI.M). The Watch_PAT RDI (PAT RDI) and oxygen desaturation index (PAT ODI) were then evaluated against the polysomnography RDI.C and RDI.M, respectively, for both Watch_PAT diagnostic nights, yielding IN-LAB and HOME-LAB comparisons. SETTING: Sleep laboratory affiliated with a tertiary-care academic medical center. PATIENTS: 30 patients referred with suspected OSA. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The polysomnography and PAT measures were compared using the mean [2 SD] of the differences and the intra-class correlation coefficient (ICC). The receiver-operator characteristic curve was used to assess optimum sensitivity and specificity and calculate likelihood ratios. For the IN-LAB comparison, there was high concordance between RDI.C and PAT RDI (ICC = 0.88, mean difference 2.5 [18.9] events per hour); RDI.M and PAT ODI (ICC = 0.95, mean difference 1.4 [12.9] events per hour; and sleep time (ICC = 0.70, mean difference 7.0 [93.1] minutes) between the test device and PSG. For the HOME-LAB comparison, there was good concordance between RDI.C and PAT RDI (ICC = 0.72, mean difference 1.4 [30.1] events per hour) and RDI.M and PAT ODI (ICC = 0.80, mean difference 1.6 [26.4] events per hour) for the test device and PSG. Home studies were performed with no technical failures. CONCLUSIONS: In a population of patients suspected of having obstructive sleep apnea, the Watch_PAT can quantify an ODI that compares very well with Medicare criteria for defining respiratory events and an RDI that compares favorably with Chicago criteria for defining respiratory events. The device can be used with a low failure rate for single use in the lab and home for self-administered testing.     

Effects of melatonin administration on daytime sleep after simulated night shift work

Disturbed sleep and on-the-job sleepiness are widespread problems among night shift workers. The pineal hormone melatonin may prove to be a useful treatment because it has both sleep-promoting and circadian phase-shifting effects. This study was designed to isolate melatonin's sleep-promoting effects, and to determine whether melatonin could improve daytime sleep and thus improve night time alertness and performance during the night shift. The study utilized a placebo-controlled, double-blind, cross-over design. Subjects (n=21, mean age=27.0 +/- 5.0 years) participated in two 6-day laboratory sessions. Each session included one adaptation night, two baseline nights, two consecutive 8-h night shifts followed by 8-h daytime sleep episodes and one recovery night. Subjects took 1.8 mg sustained-release melatonin 0.5 h before the two daytime sleep episodes during one session, and placebo before the daytime sleep episodes during the other session. Sleep was recorded using polysomnography. Sleepiness, performance, and mood during the night shifts were evaluated using the multiple sleep latency test (MSLT) and a computerized neurobehavioral testing battery. Melatonin prevented the decrease in sleep time during daytime sleep relative to baseline, but only on the first day of melatonin administration. Melatonin increased sleep time more in subjects who demonstrated difficulty in sleeping during the day. Melatonin had no effect on alertness on the MSLT, or performance and mood during the night shift. There were no hangover effects from melatonin administration. These findings suggest that although melatonin can help night workers obtain more sleep during the day, they are still likely to face difficulties working at night because of circadian rhythm misalignment. The possibility of tolerance to the sleep-promoting effects of melatonin across more than 1 day needs further investigation.     

Arousal components which differentiate the MWT from the MSLT

STUDY OBJECTIVES: The purpose of this study was to determine the relative contribution of the instruction to maintain wakefulness versus posture change as major components determining sleep latency in the MWT as compared to the MSLT. DESIGN AND SETTING: After adaptation, subjects spent 3 nights and the following days in the laboratory. On each day, Ss had eight sleep latency measurements including four sleep latency tests from two of the following conditions: Lay down and Sleep (MSLT); Lay down and stay Awake; Sit up and Sleep; Sit up and stay Awake (MWT); and sit in a chair in front of a Computer and stay awake. PARTICIPANTS: Participants were 14 young adult normal sleepers. INTERVENTIONS: NA. MEASUREMENT AND RESULTS: Significant differences in sleep latency were found for each condition with respect to all of the others except that the Computer condition did not differ from the Sit-Awake condition. Means for conditions were: Lay-Sleep -11.1 minutes; Sit-Sleep -17.7 minutes; Lay-Awake - 21.7 minutes; Sit-Awake - 29.0 minutes; Computer - 30.1 minutes. Correlations between conditions declined as subjects sat up. CONCLUSIONS: The MWT differs from the MSLT by taking advantage of the arousal system (motivation and posture) to maintain alertness (i.e., increase sleep latency). These arousal effects are additive. MSLT results may not always correlate well with MWT results because the MWT measures the combined effects of the sleep and arousal systems while the MSLT, in ideal situations, measures only sleepiness.     

Daytime continuous polysomnography predicts MSLT results in hypersomnias of central origin

In the diagnostic work‐up of hypersomnias of central origin, the complaint of excessive daytime sleepiness should be objectively confirmed by MSLT findings. Indeed, the features and diagnostic utility of spontaneous daytime sleep at 24 h continuous polysomnography (PSG) have never been investigated. We compared daytime PSG features to MSLT data in 98 consecutive patients presenting with excessive daytime sleepiness and with a final diagnosis of narcolepsy with cataplexy/hypocretin deficiency (n = 39), narcolepsy without cataplexy (n = 7), idiopathic hypersomnia without long sleep time (n = 19), and ‘hypersomnia’ with normal sleep latency at MSLT (n = 33). Daytime sleep time was significantly higher in narcolepsy‐cataplexy but similar in the other groups. Receiver operating characteristics (ROC) curves showed that the number of naps during daytime PSG predicted a mean sleep latency ≤8 min at MSLT with an area under the curve of 0.67 ± 0.05 (P = 0.005). The number of daytime sleep‐onset REM periods (SOREMPs) in spontaneous naps strikingly predicted the scheduled occurrence of two or more SOREMPs at MSLT, with an area under the ROC curve of 0.93 ± 0.03 (P < 10^?12). One spontaneous SOREMP during daytime had a sensitivity of 96% with specificity of 74%, whereas two SOREMPs had a sensitivity of 75%, with a specificity of 95% for a pathological REM sleep propensity at MSLT. The features of spontaneous daytime sleep well correlated with MSLT findings. Notably, the occurrence of multiple spontaneous SOREMPs during daytime clearly identified patients with narcolepsy, as well as during the MSLT.     

Is a polysomnographic recording prior to MSLT worth the effort?

Objective

It was recently proposed that polysomnography (PSG) may be replaced by actigraphy in order to obtain long-term sleep time prior to the multiple sleep latency test (MSLT). Polysomnography is used to assess sleep time and to detect and classify underlying sleep pathology. In the following article, the contribution of PSG to the diagnostic outcome of the MSLT is discussed.

Methods

MSLT referrals (n?=?81) with in-home polysomnography from the neurology (n?=?39, 23 women, 37 (±13) years) and pulmonary medicine (n?=?42, 20 women, 41 (±14) years) departments were analyzed. The diagnostic outcomes of the PSG and MSLT were examined.

Results

Median total sleep time prior to MSLT was 362 (range, 156–530) min. Sleep apnea (respiratory disturbance index >?15/h and >?30/h) was diagnosed in 21 and 19 patients, respectively. Periodic limb movements (PLM) were identified in 5 patients; 3 of these had a PLM arousal index >?5/h. Sleep onset REM (SOREM) was detected during PSG in 5 patients; 4 of these also had SOREM in the MSLT.

Conclusion

PSG combined with MSLT was found to improve diagnostic outcome and is highly useful for recognition of sleep-related pathology. Various sleep disorders remain undetected if ACT alone is used prior to MSLT procedures.     

Patients with primary insomnia in the sleep laboratory: do they present with typical nights of sleep?

The validity of sleep laboratory investigations in patients with insomnia is important for researchers and clinicians. The objective of this study was to examine the first‐night effect and the reverse first‐night effect in patients with chronic primary insomnia compared with good sleeper controls. A retrospective comparison of a well‐characterised sample of 50 patients with primary insomnia and 50 good sleeper controls was conducted with respect to 2 nights of polysomnography, and subjective sleep parameters in the sleep laboratory and the home setting. When comparing the first and second sleep laboratory night, a significant first‐night effect was observed across both groups in the great majority of the investigated polysomnographic and subjective variables. However, patients with primary insomnia and good sleeper controls did not differ with respect to this effect. Regarding the comparison between the sleep laboratory nights and the home setting, unlike good sleeper controls, patients with primary insomnia reported an increased subjective sleep efficiency on both nights (in part due to a reduced bed time) and an increased subjective total sleep time on the second night. These results suggest that even the second sleep laboratory night does not necessarily provide clinicians and researchers with a representative insight into the sleep perception of patients with primary insomnia. Future studies should investigate whether these findings also hold for other patient populations.     

A randomized, double-blind clinical trial comparing continuous positive airway pressure with a novel bilevel pressure system for treatment of obstructive sleep apnea syndrome

STUDY OBJECTIVES: To obtain efficacy, objective compliance, and self-assessment data from obstructive sleep apnea syndrome (OSAS) patients treated with continuous positive airway pressure (CPAP) or a novel bilevel (NBL) therapy. DESIGN: Randomized, controlled, double-blind trial. SETTING: Home treatment after diagnosis and titration by split-night polysomnography (PSG) in a sleep laboratory. PATIENTS: Twenty-seven adults (22 men) newly referred for suspected OSAS but without concomitant medical or sleep disorders. INTERVENTIONS: If the subject's apnea-hypopnea index was greater than 10 and less than 100, the CPAP was titrated during PSG and then followed by NBL titration. Treatment was randomly and blindly set to either CPAP or NBL mode for 1 month. MEASUREMENTS & RESULTS: There were no significant baseline group differences in age, body mass index, apnea-hypopnea index (mean +/- SD, CPAP group vs NBL group of 46.1 +/- 23.1/hour vs 41.8 +/- 25.8), CPAP requirement, or scores on the Epworth Sleepiness Scale and Functional Outcomes of Sleep Questionnaire. Treatment with CPAP and NBL equivalently reduced the apnea-hypopnea index during the laboratory titration (7.6 +/- 11.9/hour vs. 3.7 +/- 4.4, respectively). At 1 month, there were no significant group compliance differences as determined by percentage of nights with at least 4 hours of use (CPAP, 80.5 +/- 24 vs NBL, 77.6 +/- 24.8) and hours of use per night (CPAP, 5.6 +/- 1.4 hours/night vs NBL, 5.6 +/- 1.7). Similar improvements were seen in scores on the Epworth Sleepiness Scale and Functional Outcomes of Sleep Questionnaire. CONCLUSIONS: The NBL appeared to be as effective as CPAP for the treatment of OSAS but offered no advantages in patients receiving first-time therapy for OSAS.     

Respiratory arousals in mild obstructive sleep apnea syndrome.

The objective of the study is to identify patients with mild sleep apnea by counting not only apneas and hypopneas, but also mild respiratory events, which do not fulfill apnea or hypopnea criteria, but result in an arousal (Type-R arousal). Arousals related to body movements (Type-M arousal) were separately counted. The influence of nasal continuous positive airway pressure (nCPAP) on respiratory and movement arousals was analyzed. Daytime sleepiness before and after nCPAP and its relationship to arousal types was investigated using the Multiple Sleep Latency Test (MSLT) and a standardised questionnaire. Twenty-two patients with a mean age of 43.6 +/- 9.2 years underwent polysomnographic evaluation on a baseline night, and during three nights with nCPAP. On the baseline night, subjects presented with a mean RDI of 10.5 +/- 7.2/h, an apnea index (AI) of 1.2 +/- 1.5/h, a hypopnea index (HI) of 9.3 +/- 6.6/h, a R index of 5.2 +/- 5.9/h, and a M index of 9.7 +/- 5.6/h. Use of nCPAP lowered the RDI (p < 0.001) and the R index (p < 0.01). Mean sleep latency in the MSLT increased with nCPAP (p < 0.05) and the patient's subjective well being improved (p < 0.01). Correlation analysis revealed a relationship between Type-R arousals and RDI and HI (r = 0.5, p < 0.01) as well as between questionnaire scores and mean sleep latency. The decrease of Type-R indicates the positive effect of nCPAP. Arousal analysis and detection of mild respiratory events associated with arousals are helpful in investigating the sleep structure and in objectifying clinical symptoms and treatment success in patients with mild OSAS.     

Sleep perception and the multiple sleep latency test in patients with primary insomnia

The purpose of this study was to examine the relationship between overnight sleep perception and the daytime multiple sleep latency test (MSLT) among individuals who were primary insomnia patients (PIPs) or good sleeper controls (GSCs). We collected overnight sleep data via polysomnography (PSG), subjective sleep data via a morning questionnaire (self‐evaluated) and MSLT data via four 20‐min naps over 8 h. Subjects included 122 PIPs and 48 GSCs. Sleep perception was calculated as subjective sleep time/objective sleep time × 100%. PIPs showed a significant difference (P < 0.001) between sleep time, as determined by PSG (387.8 ± 100 min) and self‐report (226.3 ± 160 min), but no difference was obtained for GSCs (440.6 ± 53 versus 435.4 ± 65 min). The means for sleep perception were 56.4 ± 38.8% for the PIPs and 99.3 ± 13.6% for the GSCs (P < 0.001). In the PIPs group, weak but statistically significant negative correlations (r: ?0.20 to ?0.25) were found for MSLT versus sleep perception and versus self‐ and PSG‐evaluated sleep time. Compared to PIPs with low scores on the MSLT, those with high scores had less sleep perception (%), less self‐ and PSG‐evaluated sleep time and greater sleep misperception time. GSCs did not show significant correlations between MSLT and sleep measures or differences in comparisons between individuals with high and low scores on the MSLT. These results add novel data to the literature by suggesting that 24‐h hyperarousal potentially plays a key role in the pathophysiological issues of insomnia.     

Improvement of sleep apnea in patients with chronic renal failure who undergo nocturnal hemodialysis

BACKGROUND: Sleep apnea is common in patients with chronic renal failure and is not improved by either conventional hemodialysis or peritoneal dialysis. With nocturnal hemodialysis, patients undergo hemodialysis seven nights per week at home while sleeping. We hypothesized that nocturnal hemodialysis would correct sleep apnea in patients with chronic renal failure because of its greater effectiveness. METHODS: Fourteen patients who were undergoing conventional hemodialysis for four hours on each of three days per week underwent overnight polysomnography. The patients were then switched to nocturnal hemodialysis for eight hours during each of six or seven nights a week. They underwent polysomnography again 6 to 15 months later on one night when they were undergoing nocturnal hemodialysis and on another night when they were not. RESULTS: The mean (+/-SD) serum creatinine concentration was significantly lower during the period when the patients were undergoing nocturnal hemodialysis than during the period when they were undergoing conventional hemodialysis (3.9+/-1.1 vs. 12.8+/-3.2 mg per deciliter [342+/-101 vs. 1131+/-287 micromol per liter], P<0.001). The conversion from conventional hemodialysis to nocturnal hemodialysis was associated with a reduction in the frequency of apnea and hypopnea from 25+/-25 to 8+/-8 episodes per hour of sleep (P=0.03). This reduction occurred predominantly in seven patients with sleep apnea, in whom the frequency of episodes fell from 46+/-19 to 9+/-9 per hour (P= 0.006), accompanied by increases in the minimal oxygen saturation (from 89.2+/-1.8 to 94.1+/-1.6 percent, P=0.005), transcutaneous partial pressure of carbon dioxide (from 38.5+/-4.3 to 48.3+/-4.9 mm Hg, P=0.006), and serum bicarbonate concentration (from 23.2+/-1.8 to 27.8+/-0.8 mmol per liter, P<0.001). During the period when these seven patients were undergoing nocturnal hemodialysis, the apnea-hypopnea index measured on nights when they were not undergoing nocturnal hemodialysis was greater than that on nights when they were undergoing nocturnal hemodialysis, but it still remained lower than it had been during the period when they were undergoing conventional hemodialysis (P=0.05). CONCLUSIONS: Nocturnal hemodialysis corrects sleep apnea associated with chronic renal failure.     

Sleep and breathing at altitude of 3800 m--the acclimatization effect

Periodic breathing (PB) is a very common phenomenon occurring during sleep at high altitude. It consists of repetitive apneas or hypopneas of central origin and clusters of hyperpneic breaths. The aim of this study was to analyze sleep structure and periodic breathing in shift workers of a gold mine situated in Tien-Schan Mountains at 3800 m. In 12 subjects aged 36.1 +/- 9.3 yrs, polysomnography (PSG) was performed twice, on the night after the first working shift or during the day following first night shift, and the second PSG at the end of the first week of work. After one week, significant increase in REM sleep was noticed (5.2 +/- 4.0% vs. 12.0 +/- 6.7%, p < 0.05). There were no differences in sleep pattern between night sleep and sleep during daytime. During first PSG periodic breathing was seen in all subjects and occupied 14.7 +/- 16.6% of total sleep time. After one week PB decreased in 8 subjects however, in 4 subjects an increase in PB was observed (15.4 +/- 11.2 vs. 29.0 +/- 11.8% of sleep time). CONCLUSIONS: Sleep at altitude is characterized by reduction of REM sleep, which improves after a week of acclimatization. There are great individual variations in duration of periodic breathing; in some subjects an increase in PB can be seen.