Stanford Sleepiness Scale Ratings Research Articles

0239 THE INFLUENCE OF ANCESTRY ON SLEEP AND PERFORMANCE

Racial differences exist in sleep duration and circadian timing, however it is unknown whether these differences extend to cognitive performance. The current study investigated the role of ancestry on sleep and performance before and after a 9h advance of the sleep/wake episode. Twenty African-Americans (9F; 32.1 ± 7.5yr) and 17 European-Americans (8F; 29.7 ± 5.7yr) completed the study. Participants were scheduled to four baseline days each with 8h time in bed based on their habitual sleep schedule such that sleep and circadian rhythms were aligned. The sleep-wake schedule was then advanced 9h earlier (misaligned) for three days. Total sleep time (TST) was assessed with actigraphy. The Automated Neuropsychological Assessment Metrics (ANAM) test battery was administered every 3h each day starting 2h after waking. Tests included a simple reaction time task (SRT) and Stanford sleepiness scale (SSS). Mixed model ANOVAs assessed the effects of ancestry (African-American or European-American) and condition (aligned or misaligned) on sleep and performance. TST was reduced on misaligned days compared to baseline (F=18.67, p<0.001) and African-Americans slept less compared to European-Americans (F=8.58, p<0.01), especially on the first two misaligned days when the difference was 47 and 59 minutes respectively (F=6.67, p<0.01). Compared to baseline, misalignment increased SSS ratings (F=72.69, p<0.001), but did not affect the number of lapses (F=0.02, p=0.90) or median reaction time (RT)(F=0.02, p=0.88) on the SRT. While there was no effect of ancestry on SSS (F=0.22, p=0.64), there was a trend for lapses (F=3.55, p=0.07) and median RT (F=2.80, p=0.10) to be higher for African-Americans. On misaligned days, African-Americans performed worse than European-Americans at times corresponding to the end of baseline sleep (lapses, F=7.16, p<0.05; median RT, F=5.16, p<0.05). Racial disparities in sleep may be more prominent when the sleep episode is shifted, and there may be racial differences in the circadian regulation of performance. Results have implications for the sleep and performance of individuals undertaking shiftwork or transmeridan travel. R01NR007677(CIE).

A standard procedure enhances the correlation between subjective and objective measures of sleepiness.

The goal of this study was to assess whether instituting a standard procedure to minimize transient activation prior to the subjective rating of sleepiness can improve the predictive value of the rating process. Thirty young adults, aged 19 to 26 years, participated in the study. Subsequent to sleeping at home with bedtime restricted to 5 hours, they came to the sleep laboratory. They were instructed to rate their level of sleepiness on the Stanford Sleepiness Scale (SSS) and visual analog scales (VAS). A "calm-down" procedure, sitting quietly with eyes closed for 1 minute, was instituted prior to sleepiness ratings for half of the subjects (experimental group) but not for the other half of the subjects (control group). A nap trial with polysomnographic recording was then conducted, followed by a vigilance test. For the experimental group, VAS results of "sleepiness" and "alertness" both correlated significantly with sleep-onset latency during the nap (SOL: r = -.62 and .64, respectively, P values < .05) and with reaction time (RT) on the vigilance test (r = .56 and -.54, P values < .05). The SSS ratings showed significant correlation with nap SOL (r = -.58, P < .05) but not with RT on the vigilance test (r = .19, p = .52). For the control group, none of the subjective ratings showed significant correlation with objective measures. The differences between the resultant correlations for the 2 groups were statistically significant for 2 sets of correlations: the correlation between VAS of "alertness" and nap SOL and the correlation between VAS of "sleepiness" and RT on the vigilance test. The results indicate that the subjective ratings of the sleepiness state for individuals with mild sleep restriction more faithfully reflect a physiologic tendency to fall asleep as well as cognitive attentiveness when the ratings are conducted subsequent to sitting still with eyes closed for a sufficient time to minimize transient activation.

Pupillometric Assessment of Excessive Daytime Sleepiness in Narcolepsy-Cataplexy

Ten untreated patients with narcolepsy-cataplexy and age- and sex-matched normals between the ages of 20 and 71 years underwent pupillometric analyses immediately prior to each of five multiple sleep latency test sessions. Although narcoleptics were sleepier as indicated both by their Stanford Sleepiness Scale ratings and by their latencies to sleep onset, the baseline pupil diameter, pupillary light reflex, and pupillary orienting response did not differentiate between groups. Narcoleptics did, however, exhibit a significantly greater frequency of spontaneous oscillations in the dark-adapted state than did controls. These findings indicate that pupillary stability may serve as a supplementary diagnostic tool for narcolepsy-cataplexy. The results are discussed with the view that psychosensory restoration of alertness, among other extraneous variables, must be controlled when utilizing pupillometric techniques. A review of the literature indicates a variety of methodological and statistical shortcomings that must be amended. Suggestions are made for improving the reliability and validity of the pupillometric approach.

Sleepiness/Alertness on a Simulated Night Shift Following Sleep at Home with Triazolam

Physiological sleep tendency during a simulated night shift schedule was examined in 15 middle-aged subjects following daytime sleep after administration of triazolam or placebo. A double-blind, counterbalanced, crossover design involving two tours of five laboratory nights and four daytime home sleep periods was used. Triazolam lengthened daytime sleep as measured by wrist actigraph and improved nighttime alertness as measured by the MSLT. Sleepiness was most profound during the early morning hours (0430 to 0630) but improved significantly across nights for both conditions. Repeated test of sustained wakefulness latencies and simulated assembly line task performance decreased slightly across the night, but there were no significant condition effects. Subjective data tended to support objective measures, although Stanford Sleepiness Scale ratings indicated that subjects did not perceive improved alertness at night after triazolam-aided daytime sleep.

Individual Differences in the Sedating Effects of Ethanol

Twenty-four healthy, normal-sleeping, males aged 21-35 were screened for basal levels of sleepiness using the Multiple Sleep Latency Test (MSLT). Twelve subjects had basal average daily sleep latencies of less than or equal to 6 min (sleepy) and 12 had latencies of greater than or equal to 16 min (alert) on the MSLT. Subjects consumed either ethanol (0.75 mg/kg) or placebo at 0900-0930 after spending 8 hr time in bed (TIB) the previous night. Sleep latency was measured at 1000, 1200, 1400, and 1600 hr. Divided attention performance and the Stanford Sleepiness Scale (SSS) were assessed at 1100 hr. Breath ethanol concentration (BEC) was determined prior to each latency test. Ethanol decreased average daily sleep latency, divided attention scores and SSS ratings. There were individual differences in the sedating and impairing effects of ethanol, related to subjects' basal level of sleepiness/alertness. The alert subjects exhibited longer sleep latencies and higher performance scores after ethanol administration than the sleepy subjects after placebo. Subjectively the groups had a similar level of sleepiness on placebo and were similarly sedated with ethanol.

The detection of sleep onset: behavioral, physiological, and subjective convergence.

In this report, a sleep deprivation/multiple arousal paradigm was used in which response time (RT) and respiratory and electroencephalographic (EEG) measures were combined with a continuous behavioral index of arousal (a deadman switch) and frequently repeated Stanford Sleepiness Scale ratings to examine the process of falling asleep. Sleep was defined behaviorally as failure to respond to the faint auditory RT cue. Although response rates decreased significantly as EEG stages passed from W through 1 to 2, responding continued in both light "sleep" stages. Respiratory, subjective, and DM changes were more pronounced between Stages W and 1 than between Stages 1 and 2. If the criterion for wakefulness is cognitive response to external stimulation, accurate distinctions between sleep and wakefulness can only be made in EEG Stages 3, 4, and rapid eye movement sleep. If EEG is the criterion, then the data suggest that cognitive response is possible during Stages 1 and 2 "sleep". The concept of a Sleep Onset Period, characterized by lengthening response times and intermittent response failure (thereby reflecting neither true sleep nor wakefulness), may provide a useful resolution to this definitional dilemma.

Efficacy of gamma-hydroxybutyrate versus placebo in treating narcolepsy-cataplexy: Double-blind subjective measures

The efficacy of gamma-hydroxybutyrate (GHB) versus placebo for treating narcolepsy was evaluated in 20 patients with narcolepsy, 10 men and 10 women, using a double-blind counterbalanced crossover design. Each patient completed a daily sleep—wake log and questionnaire during a 14-day baseline, a 29-day placebo period, a 29-day GHB period (50 mg GHBIkglnight given 25 mg/kg h.s. and 25 mglkg 3 hr later), and a 6-day washout period after each treatment. Cataplexy frequency was significantly lower during GHB treatment than during placebo treatment ( p = 0.022). Compared to baseline values, the number of cataplexy attacks per day declined by 52% and 69% during GHB treatment weeks 1 and 4, respectively. The number of subjective arousals from sleep was less with GHB than with placebo ( p = 0.035), and the number of sleep attacks was not significantly different during GHB versus placebo treatment. GHB did not have a significant effect on subjective estimates of sleep onset latency, total sleep time, Stanford Sleepiness Scale ratings at morning wake-up, methylphenidate usage, or the number of naps per day. The results indicate that GHB is efficacious for reducing the frequency of cataplexy attacks and subjective nocturnal arousals in patients with narcolepsy within the first 4 weeks of treatment.

Relationship between sleep inertia and sleepiness: Cumulative effects of four nights of sleep disruption/restriction on performance following abrupt nocturnal awakening

Performance deficits are usually evident following both extended wakefulness (sleep deprivation effects) and immediately upon awakening from sleep (sleep inertia effects). In order to determine whether sleep inertia effects are qualitatively different from sleep deprivation effects, performance on addition tests, Stanford Sleepiness Scale (SSS) ratings, and return-to-sleep latencies (RSLs) were assessed during four nights of sleep disruption/restriction. Eight subjects were polygraphically monitored in the sleep laboratory for five consecutive nights, from 2400 to 0700. On the last four nights (after an adaptation night) subjects were awakened at 0040, 0140, 0240, 0340, 0440, and 0540 for a 20-min test session. Sleepiness ratings and performance on 5-min addition tests were measured at 1.5, 7.5, and 13.5 min post-awakening, and RSL was measured at the end of each test session. Analysis of addition test performance across nights revealed that both speed and accuracy of calculations were adversely affected by the sleep disruption/restriction procedure, indicating that increasing sleepiness exacerbates sleep performance deficits upon awakening. Although divergence of SSS ratings and addition test performance across nights was suggestive, there was no conclusive evidence that sleep inertia is qualitatively different from “typical” sleepiness.

Temporal Placement of a Nap for Alertness: Contributions of Circadian Phase and Prior Wakefulness

Napping can enhance alertness during sustained wakefulness, but the importance of the temporal placement of the nap between days and within the circadian cycle remains controversial. To resolve these issues, a between-groups study was conducted with 41 healthy, young adults permitted a 2-h nap at one of five times during a 56-h period otherwise devoid of sleep. Naps were placed 12 h apart, near the circadian peak (P) or trough (T), and were preceded by 6, 18, 30, 42, or 54 h of wakefulness. Visual reaction time (RT) performance, Stanford Sleepiness Scale (SSS) ratings, and sublingual temperature were assessed every few hours throughout the 56 h, which took place in an environment free of time cues. All groups displayed a circadian-modulated decline in RT measures and increases in SSS functions as sleep loss progressed. A nap placed at any time in the protocol improved RT performance, particularly in the lapse domain, but not SSS ratings. Comparisons within groups of circadian temperature cycles for the first versus second day of the protocol indicated that early naps (P6, T18, P30) tended to prevent the mean drop in temperature across days. The earlier naps (P6, T18) yielded more robust and longer lasting RT performance benefits, which extended beyond 24 h after the naps, despite the fact that they were comprised of lighter sleep than later naps. Circadian placement of naps (P vs. T) did not affect the results on any parameter. In terms of temporal placement, therefore, napping prior to a night of sleep loss is more important for meeting subsequent performance demands than is the circadian placement of the nap. SSS ratings suggest that the napper is not aware of these performance benefits. Because the longest lasting RT gains followed early naps, which were composed of less deep sleep than later naps, napping during prolonged sleep loss may serve to prevent sleepiness more readily than it permits recovery from it.

Disturbances in diurnal rhythms following a night of reduced sleep.

Twenty-four healthy young adult males who slept regularly for 7--8 hr completed nonlaboratory appraisals based upon dependent variables which reflected daytime alertness at 4-hr intervals from 8:15 a.m. until midnight once: (a) initially after having experienced disturbed nocturnal sleep and (b) following a control night. A statistically significant 1.8 hr average decrease in total sleep was reported during the disturbed night X = 6.0 hr) versus the control condition (X - 7.8 hr) which primarily resulted from delays and/or difficulties in falling asleep. Following disturbed nocturnal sleep a significant decline in alert wakefulness occurred predominantly at: (a) midday (12:00 noon) and/or (b) in the afternoon (4:00 p.m.) as assessed by 4 of 6 adjective check list scales and lowered body temperature levels. After the disturbed night, compared with the control condition, there was a significant diminution of the amplitude or variability in the diurnal rhythm of: (a) body temperature; (b) Stanford Sleepiness Scale ratings: (c) adjective check list scores on the (i) activation, (ii) fatigue, and (iii) performance efficiency subscales. The amplitude reduction in the diurnal rhythm was associated with a general trough during the middle of the wakefulness cycle which extended from 12:00 noon until 8:00 pm.m when various arousal indices following regular sleep attained maximal values. Subjects subsequently slept significantly longer by 1.3 hr than on the immediately preceding night of reduced sleep. There was a significant negative correlation between relative levels of temperature in the morning and sleep duration reported on the disturbed night. Greater accumulations of sleep reported during the disturbed night occurred when temperature levels corresponded with values in the control condition.

Sleepiness and Sleep State on a 90‐Min Schedule

ABSTRACTThe effects of REM and slow wave sleep (SWS) on subjective sleepiness were studied in 10 subjects placed on a 90‐min sleep‐wakefulness schedule for either 51/3 or 6 (24‐hr) days. Subjects were permitted to sleep for 30‐min periods separated by 60 min of enforced wakefulness. Sleep recordings showed that sleep onset REM periods occurred frequently; REM and SWS appeared during the same sleep period only 27 times; and REM sleep tended to occur on sleep periods that alternated with SWS periods. Sleepiness was measured using the Stanford Sleepiness Scale (SSS) given 15 min before (pre‐sleep) and 15 min after (post‐sleep) each sleep period. Average SSS ratings showed a 24‐hr fluctuation in sleepiness. In addition, negative and positive SSS changes tended to alternate with each 90‐min period. Significant correlations were found with post‐sleep SSS ratings and SWS and with pre‐sleep SSS ratings and REM sleep. Differences between pre‐ and post‐sleep SSS scores were also correlated with the sleep states: increased sleepiness was correlated with SWS and decreased sleepiness with REM sleep.

Quantification of sleepiness: a new approach.

ABSTRACTThe Stanford Sleepiness Scale (SSS) is a self‐rating scale which is used to quantify progressive steps in sleepiness. The present study investigated whether the SSS cross‐validates with performance on mental tasks and whether the SSS demonstrates changes in sleepiness with sleep loss. Five college student Ss were given a brief test of memory and the Wilkinson Addition Test in 2 test sessions and The Wilkinson Vigilance Test in 2 other sessions spaced throughout a 16‐hr day for 6 days. Ss made SSS ratings every 15 min during their waking activities. On night 4, Ss underwent all night sleep deprivation. On all other nights, Ss were allowed only 8 hrs in bed. Mean SSS ratings correlated r= .68 with performance on the Wilkinson Tests. Discrete SSS ratings correlated r= .47 with performance on the memory test. Moreover, mean baseline SSS ratings were found to be significantly lower than corresponding ratings of the deprivation period.