Effects of rapid versus slow accumulation of eight hours of sleep loss

The present study assessed alertness, memory, and performance following three schedules of approximately 8 hr of sleep loss (slow, intermediate, and rapid accumulation) in comparison to an 8-hr time in bed (TIB) sleep schedule. Twelve healthy individuals aged 21-35 completed each of four conditions according to a Latin Square design: no sleep loss (8-hr TIB for 4 nights; 2300-0700), slow (6-hr TIB for 4 nights; 0100-0700), intermediate (4-hr TIB for 2 nights; 0300-0700), and rapid (0-hr TIB for 1 night) sleep loss. On each day, participants completed a multiple sleep latency test (MSLT), a probed-recall memory task, a psychomotor vigilance task, a divided attention task, and the Profile of Mood States. "Rapid" sleep loss produced significantly more impairment on tests of alertness, memory, and performance compared to the "slow" accumulation of a comparable amount of sleep loss. The impairing effects of sleep loss vary as a function of rate, suggesting the presence of a compensatory adaptive mechanism operating in conjunction with the accumulation of a sleep debt.     

The Alerting Effects of Naps in Sleep-Deprived Subjects

The effect of napping for varying durations after one night of sleep deprivation was examined. Sleep latency tests were used to determine levels of sleepiness/alertness at 2, 4, 6, and 8 hrs following a morning nap of 0, 15, 30, 60, or 120 min duration. Ten normal-sleeping, young adult volunteers spent two consecutive days and the intervening night in the sleep laboratory on each of five weeks. Baseline sleep latencies were recorded the first day, sleep was deprived that night, a nap was taken at 0900 hrs, and sleep latencies were again recorded on the second day. The naps had differential alerting effects related to their duration, but none of the naps returned mean sleep latency for the 8 hrs to its basal levels. Alertness increased with nap duration, reaching its highest level with a 60-min nap; the 120-min nap was no more alerting than the 60-min nap. During the second hour of the 120-min nap, sleep became more fragmented with more shifts to stage 1 sleep or wake. Increased alertness was not strongly related to the sleep stage composition of the naps, the best predictor being minutes of slow wave sleep. Increased alertness was not detected until the second latency test 4 hrs after napping.     

Ethanol and sleep loss: a "dose" comparison of impairing effects

STUDY OBJECTIVES: Studies to assess the risks associated with sleep loss relative to the well-documented risks of alcohol are limited in number and design. This study compared the "dose"-related sedative, performance-impairing, and amnestic effects of sleep loss to those of ethanol ingestion. DESIGN: Mixed-design experiment with random assignment to a sleep loss (n=12) or ethanol (n=20) group, with each participant assessed under 4 conditions. PARTICIPANTS: Thirty-two healthy normal adult volunteers, aged 21 to 35 years. INTERVENTIONS: In sleep loss, participants had 8, 6, 4, and 0 hours time in bed, producing 0, 2, 4, and 8 hours of sleep loss. For ethanol, participants ingested 0.0 g/kg, 0.3 g/kg, 0.6 g/kg, and 0.9 g/kg ethanol from 8:30 AM to 9:00 AM after 8 hours of time in bed the previous night. Each participant received his or her 4 doses of ethanol or sleep loss in a Latin square design with 3 to 7 days between doses. MEASUREMENTS: All subjects completed the Multiple Sleep Latency Test (MSLT) at 9:30 AM, 11:30 AM, 1:30 PM, 3:30 PM, and 5:30 PM and a performance battery at 10:00 AM, 12:00 NOON, 2:00 PM, and 4:00 PM consisting of memory, psychomotor vigilance, and divided attention tests. RESULTS: Ethanol and sleep loss reduced the average daily sleep latency on the MSLT, both as a linear function of dose, with sleep loss in hours being 2.7 times more potent than ethanol in grams per kilogram. Ethanol and sleep loss also slowed reaction time on the psychomotor vigilance test in a linear dose-related function with the 2 being equipotent in their impairing effect. On the divided attention test, tracking deviations were increased by both ethanol and sleep loss in an equipotent and linear dose-related function. Memory recall was reduced in a linear dose-related function by both ethanol and sleep loss with ethanol being slightly more potent. Finally, sleep loss doses produced a linear decrease in self-rated quality of performance, while only at the highest ethanol dose was performance rated as poorer. CONCLUSIONS: At the studied doses, sleep loss was more potent than ethanol in its sedative effects but comparable in effects on psychomotor performance. Ethanol produced greater memory deficits, and subjects were less aware of their overall performance impairment.     

No effect of 8-week time in bed restriction on glucose tolerance in older long sleepers

The aim of this study was to investigate the effects of 8 weeks of moderate restriction of time in bed (TIB) on glucose tolerance and insulin sensitivity in healthy older self-reported long sleepers. Forty-two older adults (ages 50-70 years) who reported average sleep durations of >or=8.5 h per night were assessed. Following a 2-week baseline, participants were randomly assigned to two 8-week treatments: either (i) TIB restriction (n = 22), which involved following a fixed sleep schedule in which time in bed was reduced by 90 min compared with baseline; (ii) a control (n = 18), which involved following a fixed sleep schedule but no imposed change of TIB. Sleep was monitored continuously via wrist actigraphy recordings, supplemented with a daily diary. Glucose tolerance and insulin sensitivity were assessed before and following the treatments. Compared with the control treatment, TIB restriction resulted in a significantly greater reduction of nocturnal TIB (1.39 +/- 0.40 h versus 0.14 +/- 0.26 h), nocturnal total sleep time (TST) (1.03 +/- 0.53 h versus 0.40 +/- 0.42 h), and 24-h TST (1.03 +/- 0.53 h versus 0.33 +/- 0.43 h) from baseline values. However, no significant effect of TIB restriction was found for glucose tolerance or insulin sensitivity. These results suggest that healthy older long sleepers can tolerate 8 weeks of moderate TIB restriction without impairments in glucose tolerance or insulin sensitivity.     

Ethanol and caffeine effects on daytime sleepiness/alertness

Eighteen normal-sleeping young (mean age 25.6 years) volunteers received either ethanol (0.75 g/kg producing blood ethanol concentrations of 71.1 +/- 24.3 mg/100 ml on average) or caffeine (4.0 mg/kg dissolved in 300 ml of 97% caffeine-free instant coffee) at 0920-0950 h after spending 5, 8, or 11 h time in bed (TIB) the previous night. Latency to sleep onset was tested at 1000, 1200, 1400, and 1600 h. Mean sleep latency differed significantly between drugs on each day of testing, with subjects being sleepier after ethanol than caffeine. On day 2 the TIB manipulation produced significant differences in latency, with the 11-h condition differing from both the 8- and 5-h conditions. The significant interaction revealed that in fully rested subjects (11-h TIB), ethanol did not produce sleepiness to the degree it did after 5 or 8 h in bed. In this condition latencies were similar to those of the caffeine and 5- or 8-h TIBs.     

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.     

Neurobehavioral Dynamics Following Chronic Sleep Restriction: Dose-Response Effects of One Night for Recovery

Objective:

Establish the dose-response relationship between increasing sleep durations in a single night and recovery of neurobehavioral functions following chronic sleep restriction.

Design:

Intent-to-treat design in which subjects were randomized to 1 of 6 recovery sleep doses (0, 2, 4, 6, 8, or 10 h TIB) for 1 night following 5 nights of sleep restriction to 4 h TIB.

Setting:

Twelve consecutive days in a controlled laboratory environment.

Participants:

N = 159 healthy adults (aged 22-45 y), median = 29 y).

Interventions:

Following a week of home monitoring with actigraphy and 2 baseline nights of 10 h TIB, subjects were randomized to either sleep restriction to 4 h TIB per night for 5 nights followed by randomization to 1 of 6 nocturnal acute recovery sleep conditions (N = 142), or to a control condition involving 10 h TIB on all nights (N = 17).

Measurements and Results:

Primary neurobehavioral outcomes included lapses on the Psychomotor Vigilance Test (PVT), subjective sleepiness from the Karolinska Sleepiness Scale (KSS), and physiological sleepiness from a modified Maintenance of Wakefulness Test (MWT). Secondary outcomes included psychomotor and cognitive speed as measured by PVT fastest RTs and number correct on the Digit Symbol Substitution Task (DSST), respectively, and subjective fatigue from the Profile of Mood States (POMS). The dynamics of neurobehavioral outcomes following acute recovery sleep were statistically modeled across the 0 h-10 h recovery sleep doses. While TST, stage 2, REM sleep and NREM slow wave energy (SWE) increased linearly across recovery sleep doses, best-fitting neurobehavioral recovery functions were exponential across recovery sleep doses for PVT and KSS outcomes, and linear for the MWT. Analyses based on return to baseline and on estimated intersection with control condition means revealed recovery was incomplete at the 10 h TIB (8.96 h TST) for PVT performance, KSS sleepiness, and POMS fatigue. Both TST and SWE were elevated above baseline at the maximum recovery dose of 10 h TIB.

Conclusions:

Neurobehavioral deficits induced by 5 nights of sleep restricted to 4 h improved monotonically as acute recovery sleep dose increased, but some deficits remained after 10 h TIB for recovery. Complete recovery from such sleep restriction may require a longer sleep period during 1 night, and/or multiple nights of recovery sleep. It appears that acute recovery from chronic sleep restriction occurs as a result of elevated sleep pressure evident in both increased SWE and TST.

Citation:

Banks S; Van Dongen HPA; Maislin G; Dinges DF. Neurobehavioral dynamics following chronic sleep restriction: dose-response effects of one night for recovery. SLEEP 2010;33(8):1013–1026.     

多次睡眠潜伏期试验方法与临床应用

目的：研究多次睡眠潜伏期试验（muhiple sleep latency test MSLT）方法和操作步骤。方法：应用多导睡眠图（PSG）进行多次睡眠潜伏期试验，分析多次试验的睡眠次数、睡眠潜伏期和REM出现次数。结果：该方法取得了较好的临床应用效果。结论：MSLT对发作性睡病、阻塞性睡眠呼吸暂停、原发性嗜睡症和睡眠中周期性腿动等疾病的诊断和鉴别诊断具有重要参考价值。     

Sleep and wakefulness in normal preadolescent children

Eighteen healthy children, 9 boys and 9 girls, between 8 and 12 years of age were examined with polygraphic sleep records, multiple sleep latency tests (MSLTs), and measurements of reaction times. Sleep was recorded at home on Oxford Medilog 9 channel cassette tape recorders (Oxford Medical Systems, Abingdon, U.K.) and sleep staging was performed from the screen of the display unit. Two consecutive nights were recorded. MSLT was done in the laboratory. The subjects were given 30 min to fall asleep on four occasions during the day after the last recorded night of sleep. Reaction times were measured repeatedly between each MSLT trial. More slow wave sleep was found in this study compared to others. Also, the first night effect was slight. It is proposed that this is due to the fact that the recordings were performed at home. The initial sleep cycle was incomplete in almost all subjects. A sleep stage with traits of both rapid eye movement (REM) and non-REM could be seen in this cycle, probably representing an abortive REM period. MSLT confirmed the low daytime sleepiness in healthy preadolescent children. A sleep latency of 10 min or less on two or more sleep trials, or a daily mean sleep latency of less than 20 min, is rarely seen in this age group. The reaction times were within normal limits for the age of the subjects. Nighttime sleep values, daytime sleep latencies, and reaction times were not correlated in these normal-sleeping children.     

Scoring reliability of the multiple sleep latency test in a clinical population

STUDY OBJECTIVES: To determine intrarater and interrater scoring reliability of the multiple sleep latency test (MSLT) in a population of sleep clinic patients. DESIGN: N/A. SETTING: Urban sleep center. PATIENTS: 200 consecutive sleep center patients (diagnoses included: obstructive sleep apnea, narcolepsy, periodic-limb-movement, and individuals with no diagnosis). INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: MSLTs were recorded and scored according to standard clinical procedures. One of four clinical polysomnographers and one of seven polysomnographic technologists scored each MSLT. All MSLTs were then rescored by the same polysomnographer. The intrarater reliability coefficient for mean MSLT score was .87 and interrater reliability was .90. Coefficients for the mean number of REM onsets during the MSLT were .81 for intrarater and .88 for interrater reliability. Intrarater and interrater agreement (kappa coefficients) for the presence of at least one REM onset during the MSLT was .78 and .86, respectively. For the presence of greater than one REM onset, a kappa of .78 was obtained for intrarater agreement and .91 for interrater agreement. CONCLUSIONS: The clinical MSLT displays excellent interrater and intrarater reliability estimates for both sleep latency and REM onset scores in a sleep-disordered population.     

Actigraphy validation with insomnia

STUDY OBJECTIVE: Actigraphy, a method of inferring sleep from the presence or absence of wrist movement, has been well validated against polysomnography in trials with people without insomnia. However, the small amount of literature on validation with insomniacs has revealed an actigraphy bias toward overscoring sleep. The current validation trial with insomniacs used the largest number of subjects to date in such research and attracted participants with diverse demographic characteristics. DESIGN: People with insomnia slept 1 night in the laboratory while simultaneously being monitored by polysomnography, actigraphy (high-sensitivity algorithm of the Mini Mitter AW64 Actiwatch), and morning sleep diary. SETTING: Sleep disorders center. PARTICIPANTS: Participants were 57 volunteers from the community, 26 men and 31 women, ranging in age from 21 to 87 years. All participants satisfied conservative criteria for insomnia. The sample included subjects with primary insomnia, subjects with comorbid insomnia, and hypnotic users with current insomnia complaints. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Actigraphy was successfully validated on 4 measures of sleep pattern--number of awakenings, wake time after sleep onset, total sleep time, and sleep efficiency percentage--based on nonsignificant mean differences and significant correlation between actigraphy and polysomnography. Sleep-onset latency with actigraphy was not significantly different from polysomnography but was weakly correlated with polysomnography. Hypnotic use contributed to actigraphic overscoring of sleep. CONCLUSIONS: Actigraphy proved to be a satisfactory objective measure of sleep on 4 of 5 sleep parameters, but these results are specific to this particular instrument using this particular algorithm and should not be construed as a blanket endorsement of actigraphy for measuring insomnia.     

A double-blind study in healthy volunteers to assess the effects on sleep of pregabalin compared with alprazolam and placebo

STUDY OBJECTIVES: To assess the effects of pregabalin compared with alprazolam and placebo on aspects of sleep in healthy volunteers. DESIGN: Randomized, double-blind, placebo- and active-controlled, 3-way crossover. SETTING: Single research center. PARTICIPANTS AND INTERVENTIONS: Healthy adult (12 men) volunteers (N=24) received oral pregabalin 150 mg t.i.d., alprazolam 1 mg t.i.d., and placebo t.i.d. for 3 days. MEASUREMENTS AND RESULTS: Objective sleep was measured by an 8-channel polysomnograph; subjective sleep was measured using the Leeds Sleep Evaluation Questionnaire. Compared with placebo, pregabalin significantly increased slow-wave sleep both as a proportion of the total sleep period and the duration of stage 4 sleep. Alprazolam significantly reduced slow-wave sleep. Pregabalin and alprazolam produced modest, but significant, reductions in sleep-onset latency compared with placebo. Rapid eye movement sleep latency after pregabalin was no different than placebo but was significantly shorter than that found with alprazolam. Although there were no differences between the active treatments, both pregabalin and alprazolam reduced rapid eye movement sleep as a proportion of the total sleep period compared with placebo. Pregabalin also significantly reduced the number of awakenings of more than 1 minute in duration. Leeds Sleep Evaluation Questionnaire ratings of the ease of getting to sleep and the perceived quality of sleep were significantly improved following both active treatments, and ratings of behavior following awakening were significantly impaired by both drug treatments. CONCLUSIONS: Pregabalin appears to have an effect on sleep and sleep architecture that distinguishes it from benzodiazepines. Enhancement of slow-wave sleep is intriguing, since reductions in slow-wave sleep have frequently been reported in fibromyalgia and general anxiety disorder.     

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.     

Sleepiness/alertness on a simulated night shift schedule and morningness-eveningness tendency.

This study examined the influence of morningness-eveningness on night shift sleepiness in 15 subjects. Sleepiness was assessed during a five-night protocol involving the multiple sleep latency test (MSLT), repeated test of sustained wakefulness (RTSW) and the Stanford Sleepiness Scale (SSS). Daytime sleep was estimated by sleep diaries and wrist actigraphy. The sample was divided by median score on the Horne and Ostberg Morningness-Eveningness Questionnaire. Physiological sleep tendency was significantly worse between 0030 and 0430 hours for the Morning Tendency group than for the Non-Morning Tendency group. The Morning Tendency group reported obtaining less daytime sleep than the Non-Morning Tendency group; however, there was no difference between groups in total daytime sleep estimated by actigraphy. This preliminary study suggests that morning types are sleepier during night shift hours than non-morning types.     

The prevalence of multiple sleep-onset REM periods in a population-based sample

STUDY OBJECTIVE: The presence of 2 or more sleep-onset rapid eye movement periods (SOREMPs) on a Multiple Sleep Latency Test (MSLT) has been used as 1 of the criteria for the diagnosis of narcolepsy and is thought to be specific to this disorder. However, previous studies have shown the prevalence of SOREMPS in healthy volunteers and apneic patients to be higher than expected. The present study determined the prevalence of 2 or more SOREMPs in a representative sample of the population from southeast Michigan and investigated potential associations with other sleep-related variables. DESIGN: Cross-sectional laboratory-based analysis. SETTINGS: Sleep disorders clinic. PARTICIPANTS: Population-based sample. INTERVENTIONS: N/A. MEASUREMENTS: A population-based sample of 333 subjects was assessed by nocturnal polysomnography and daytime MSLT (5 naps), and an additional 206 subjectively sleepy people were also assessed (total = 539). Sample demographics were comparable to the 2000 census. Epworth Sleepiness Scale scores were also determined. Groups were formed based on a median split of each sleep variable (Epworth Sleepiness Scale, MSLT, total sleep time from nocturnal polysomnography) for comparisons of SOREMPs in each group. RESULTS: The prevalence of 2 or more SOREMPs was 3.9%. Only mean sleep latency on the MSLT was a discriminator for the presence of 2 or more SOREMPs (short latency = 6.3%, long latency = 1.9%, p < .05). Among the subjects who had an MSLT of 5 minutes or less (an indicator of a pathologic level of sleepiness), 9.5% had 2 or more SOREMPS. CONCLUSIONS: The overall prevalence of 2 or more SOREMPs in our sample is 3.9%. Interestingly, of the variables assessed (MSLT, Epworth Sleepiness Scale, and total sleep time from nocturnal polysomnography), objective sleepiness, as determined by the MSLT, was the only measure significantly associated with 2 or more SOREMPs. Therefore, subpopulations with excessive sleepiness (eg, shift workers, young adults, patients with apnea) are likely to have a greater prevalence of SOREMPs.     

A dose–response study of total sleep time and the ability to maintain wakefulness

The apparent connection between sleep debt, performance decrements and workplace accidents has generated a need for feasible vigilance tests that focus on the quantification of daytime sleepiness in occupational settings. The objective of this study was to evaluate the sensitivity of the Maintenance of Wakefulness Test (MWT) to acute sleep deprivation of various doses. Eight healthy female volunteers, mean age 28.9 years (range 23–36), participated in this laboratory study. After an adaptation night, the subjects were assigned to four counterbalanced, randomly ordered night sleep conditions. These four conditions allowed for a time in bed (TIB) of 0, 2, 4 or 8 h, producing a total sleep time of 0, 113, 218 and 427 min, respectively. The ability to sustain wakefulness was measured after the TIB period at 11.00 and 17.00 hours by the MWT. Analysis of variance with repeated measures was used to study the dependence of MWT sleep latencies on the immediately prior TIB period. Both the latency of stage 1 sleep onset and the appearance of slow eye movements reduced significantly with increased sleep loss. The quantitative relationship between the previous total sleep time and the subsequent MWT sleep latencies followed an exponentially decaying function showing a high sensitivity to acute, severe night sleep loss but low sensitivity to less severe sleep restrictions. It is concluded that the MWT seems to be a sensitive method for the estimation of acute sleep deprivation. The test results appear, however, non-linearly related to the earlier sleep debt.     

Evaluation of antihistamine-related daytime sleepiness

The daytime sleepiness potentially associated with antihistamines was evaluated by the multiple sleep latency test (MSLT) in a study comparing terfenadine with placebo. According to a double-blind, randomized, cross-over design, 12 healthy men were given either 120 mg terfenadine or placebo once daily in the morning, for 3 consecutive days with a 5-day interval. EEG-polygraphic recordings were made each study day at 9:30 and 11:30 a.m., and 1:30, 3:30, and 5:30 p.m., and the tendency to fall asleep was measured. All mean stage-1 sleep latencies throughout the study failed to show any significant difference between terfenadine and placebo. Accordingly, psychomotor performance assessed by visual and auditory reaction time did not change after treatment. The results of this study confirmed that terfenadine does not induce daytime sleepiness as objectively measured by MSLT.     

Excessive daytime somnolence and increased rapid eye movement pressure in myotonic dystrophy

STUDY OBJECTIVES: Sleep studies at Duke University Medical Center were retrospectively reviewed to investigate causes of excessive daytime sleepiness (EDS) in our myotonic dystrophy1 (DM1) patient population, identified by an abnormal CTG expansion on chromosome 19. Excessive daytime sleepiness, an accentuated desire for sleep or the occurrence of sleep episodes that interfere with normal wakefulness, is common in patients with DM1. Sleep abnormalities, such as central and obstructive sleep apnea, have been extensively reported; however, many DM1 patients suffer from EDS in the absence of any identified respiratory dysrhythmia. DESIGN: Nineteen DM1 patients, with the clinical diagnosis and genetic confirmation in the proband or a related family member, had a sleep evaluation. Polysomnogram (PSG) and mean sleep latency test (MSLT) results were retrospectively reviewed. SETTING: N/A. PARTICIPANTS: N/A. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Most DM1 patients demonstrated grade 3 (distal weakness) or grade 4 (mild to moderate proximal weakness) on the myotonic dystrophy impairment rating scale. All patents had a PSG, with 13 patients having an MSLT the following day. Clinically significant respiratory abnormalities on PSG, defined in this study as a respiratory disturbance index > 15 and/or upper airway resistance syndrome, could not explain the EDS observed in 14 of 19 patients. Decreased mean sleep latency was observed in 12 of 13 patients evaluated by MSLT, while sleep onset REM sleep was seen in 8 of 13 patients. Pathologic REM onset (2 or more SOREMs on MSLT) was seen in 5 of 13 patients, with 3 of those 5 patients having a PSG with RDI < or = 5. CONCLUSIONS: Most DM1 patients did not have significant respiratory abnormalities on PSG to explain the manifested EDS. Objective sleepiness is common in DM1, and pathologic REM pressure can be commonly observed. These observations imply an intrinsic hypersomnolence sometimes accompanied by abnormal REM pressure may be an integral part of EDS in DM1 patients.     

The association between daytime sleepiness and sleep-disordered breathing in NREM and REM sleep

BACKGROUND: Daytime sleepiness is common in patients with sleep-disordered breathing. Although respiratory events during sleep are associated with the occurrence of daytime sleepiness, the differential impact of these events during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep on daytime sleepiness has not been well characterized. STUDY OBJECTIVES: To determine the effect of respiratory events during REM sleep and NREM sleep on daytime sleepiness, as assessed by the multiple sleep latency test (MSLT). DESIGN: Cross-sectional study. SETTING: University-based sleep disorders laboratory. PARTICIPANTS: Patients referred for polysomnography and daytime MSLT (n=1,821). INTERVENTIONS: N/A MEASUREMENTS AND RESULTS: The study sample was initially divided into quartiles based on the level of the apnea-hypopnea index (AHI) during NREM sleep. Within the first NREM-AHI quartile (NREM-AHI < 8.3 events/hr), the association between REM-related respiratory events and daytime sleepiness was examined using the method of Kaplan-Meier analysis and Cox proportional hazards regression. After adjusting for age, gender, body mass index, and the duration of NREM and REM sleep, REM-AHI was not associated with daytime sleepiness (Relative Risk: 1.01; 95%CI: 0.94-1.10). Similarly, no significant association was observed between REM-AHI and the MSLT in patients within the second through fourth NREM-AHI quartiles. In contrast, increasing severity of disordered breathing during NREM sleep was associated with daytime sleepiness. For a 10-point increase in NREM-AHI, the adjusted relative risks for daytime sleepiness in the second through fourth NREM-AHI quartile were 1.21 (95%CI: 1.01-1.46), 1.20 (95%CI: 1.05-1.37), and 1.10 (95%CI: 1.04-1.16), respectively. CONCLUSION: Sleep-disordered breathing during NREM sleep, but not REM sleep, is associated with increased risk of daytime sleepiness.     

Effects of afternoon "siesta" naps on sleep, alertness, performance, and circadian rhythms in the elderly

STUDY OBJECTIVES: To determine the effects of a 90-minute afternoon nap regimen on nocturnal sleep, circadian rhythms, and evening alertness and performance levels in the healthy elderly. DESIGN AND SETTING: Nine healthy elderly subjects (4m, 5f, age range 74y-87y) each experienced both nap and no-nap conditions in two studies each lasting 17 days (14 at home, 3 in the laboratory). In the nap condition a 90-minute nap was enforced between 13:30 and 15:00 every day, in the no-nap condition daytime napping was prohibited, and activity encouraged in the 13:30-15:00 interval. The order of the two conditions was counterbalanced. PARTICIPANTS: N/A INTERVENTIONS: N/A MEASUREMENTS: Diary measures, pencil and paper alertness tests, and wrist actigraphy were used at home. In the 72 hour laboratory studies, these measures were augmented by polysomnographic sleep recording, continuous rectal temperature measurement, a daily evening single trial of a Multiple Sleep Latency Test (MSLT), and computerized tests of mood, activation and performance efficiency. RESULTS: By the second week in the "at home" study, an average of 58 minutes of sleep was reported per siesta nap; in the laboratory, polysomnography confirmed an average of 57 minutes of sleep per nap. When nap and no-nap conditions were compared, mixed effects on nocturnal sleep were observed. Diary measures indicated no significant difference in nocturnal sleep duration, but a significant increase (of 38 mins.) in 24-hour Total Sleep Time (TST) when nocturnal sleeps and naps were added together (p<0.025). The laboratory study revealed a decrease of 2.4% in nocturnal sleep efficiency in the nap condition (p<0.025), a reduction of nocturnal Total Sleep Time (TST) by 48 mins. in the nap condition (p<0.001) which resulted primarily from significantly earlier waketimes (p<0.005), but no reliable effects on Wake After Sleep Onset (WASO), delta sleep measures, or percent stages 1 & 2. Unlike the diary study, the laboratory study yielded no overall increase in 24-hour TST consequent upon the siesta nap regimen. The only measure of evening alertness or performance to show an improvement was sleep latency in a single-trial evening MSLT (nap: 15.6 mins., no nap: 11.5 mins., p<0.005). No significant change in circadian rhythm parameters was observed. CONCLUSIONS: Healthy seniors were able to adopt a napping regimen involving a 90-minute siesta nap each day between 13:30 and 15:00, achieving about one hour of actual sleep per nap. There were some negative consequences for nocturnal sleep in terms of reduced sleep efficiency and earlier waketimes, but also some positive consequences for objective evening performance and (in the diary study) 24-hour sleep totals. Subjective alertness measures and performance measures showed no reliable effects and circadian phase parameters appeared unchanged.