Cognitive function following acute sleep restriction in children ages 10-14.

STUDY OBJECTIVES: Various aspects of human performance were assessed in children after sleep loss. PARTICIPANTS: Sixteen children (7 males, 9 females) between the ages of 10 and 14 years. DESIGN AND INTERVENTIONS: Children were randomly assigned to either a control (CTRL) group, with 11 hours in bed, or an experimental sleep restriction (SR) group, with 5 hours in bed, on a single night in the sleep laboratory. MEASUREMENTS: Both groups were evaluated the following day with a battery of performance and sleepiness measures. Psychomotor and cognitive performance tests were given during four 1-hour testing sessions at 2-hour intervals. RESULTS: A multiple sleep latency test (MSLT) documented shorter latencies for SR children than controls. Significant treatment differences were discovered in three of four variables of verbal creativity, including fluency, flexibility, and average indices. There were also group differences found on the Wisconsin Card Sorting Test (WCST), which may be indicative of difficulty learning new abstract concepts. Measures of rote performance and less-complex cognitive functions, including measures of memory and learning and figural creativity, did not show differences between groups, perhaps because motivation could overcome sleepiness-related impairment for these tasks. CONCLUSIONS: Higher cognitive functions in children, such as verbal creativity and abstract thinking, are impaired after a single night of restricted sleep, even when routine performance is relatively maintained.

Effects of triazolam on sleep, daytime sleepiness, and morning stiffness in patients with rheumatoid arthritis.

OBJECTIVE: To evaluate the effects of triazolam upon insomnia and daytime sleepiness in patients with rheumatoid arthritis (RA). METHODS: Triazolam or placebo was administered during two 7 night periods to 15 patients with RA in a double blind crossover study. Polysomnographic recordings were conducted on the last 2 nights of each condition, and multiple sleep latency tests and mood and arthritis assessments were performed during the intervening day in each condition. RESULTS: In the triazolam condition, total sleep time was increased, daytime sleepiness was reduced, and morning stiffness was improved compared to placebo. Objective measures of sleep fragmentation were unchanged. Clinical arthritis assessments were similar during both conditions. CONCLUSION: Short term hypnotic therapy improves sleep in patients with RA and appears to improve morning stiffness and daytime sleepiness.

The effects of caffeine on simulated night-shift work and subsequent daytime sleep.

Thirty healthy volunteers were randomly assigned to either a caffeine or a placebo group to investigate the alerting effects of caffeine at night. Subjects adhered to a simulated night-shift schedule for 5 consecutive nights. On the first 3 nights, 2 mg/kg caffeine was added to decaffeinated coffee at 2220 and 0120 hours for the caffeine group. On nights 4 and 5 both groups received placebo. Each night, subjects completed five 60-minute sessions of a computerized simulated assembly line performance task (SALT), a multiple sleep latency test (MSLT) and questionnaires. Daytime sleep was recorded in the laboratory between 0900 and 1700 hours each day following nighttime testing. Caffeine decreased physiological sleep tendency on the night shift compared with placebo; however, the two groups performed at equivalent levels on the SALT. On nights 4 and 5, when both groups received placebo, there were no differences between the groups on the MSLT, suggesting the absence of a discontinuation effect. There were no differences on daytime polysomnograms between the groups.

Sleepiness and performance during three-day administration of cetirizine or diphenhydramine.

OBJECTIVE: The sedative effects of cetirizine (10 mg once daily), diphenhydramine (50 mg three times daily), and placebo, each administered during a 3-day period, were compared with objective measures of sleepiness and performance. METHODS: Twelve atopic subjects received each of the three treatments for 3 consecutive days in a double-blind Latin square design. Subjects received either cetirizine at 8:00 AM and placebo at 3:00 PM and 10:00 PM; diphenhydramine at 8:00 AM, 3:00 PM, and 10:00 PM; or placebo at all three times. Sleepiness was measured on days 1 and 3 with the multiple sleep latency test at 9:00 AM, 11:00 AM, 1:00 PM, 3:00 PM, and 5:00 PM. Performance was assessed with a 60-minute simulated assembly line task at 9:30 AM, 11:30 AM, 1:30 PM, and 3:30 PM. Nightly sleep duration was estimated with actigraphy. RESULTS: Compared with placebo and cetirizine, diphenhydramine produced marked impairment only on the first day of drug administration. The multiple sleep latency test and the simulated assembly line task values remained stable across days with cetirizine and placebo but improved with diphenhydramine, resulting in no differences among the three conditions on the third day. CONCLUSION: Unlike cetirizine, diphenhydramine produced acute impairment of alertness and performance. By the third day of administration, however, this impairment was no longer present, apparently because of development of tolerance to the sedative effects.

Two- and 4-hour bright-light exposures differentially effect sleepiness and performance the subsequent night.

The effect of two durations of bright light upon sleepiness and performance during typical night shift hours was assessed. Thirty normal, healthy young adults participated in a 2-night protocol. On the 1st night subjects were exposed to bright or dim light beginning at 2400 hours, under one of the following three conditions: bright light for 4 hours, dim light for 2 hours followed by bright light for 2 hours or dim light for 4 hours. Following light exposure, subjects remained awake until 0800 hours in a dimly lit room and slept in the laboratory between 0800 and 1600 hours, during which time sleep was estimated with actigraphy. Throughout the 2nd night, the multiple sleep latency test (MSLT), simulated assembly line task (SALT) performance, and subjective sleepiness were recorded. The single, 4-hour exposure to bright light was found to significantly increase MSLT scores and improve SALT performance during the early morning hours on the night following bright-light exposure. No significant effects were noted with a 2-hour exposure. The most likely explanation for these findings is a phase delay in the circadian rhythm of sleepiness-alertness.

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.

Simulated assembly line performance following ingestion of cetirizine or hydroxyzine.

Twelve healthy subjects participated in three daytime work periods, in a double-blind repeated measures Latin square design. Subjects received cetirizine (10 mg), hydroxyzine (25 mg), or placebo at 0800. Performance was measured each day during eight 50-minute test periods on a simulated assembly line task between 0830 and 1700. Before entry into the study, subjects were trained to a minimum 80% correction rate on the performance task. Performance decrements were consistently associated with hydroxyzine but not with cetirizine. Subjects made fewer correct responses with hydroxyzine compared with both cetirizine and placebo. Subjectively, participants reported feeling sleepier and performing worse during the hydroxyzine condition than following placebo. Cetirizine, however, did not differ from the other two conditions on self-assessments of alertness or performance. These findings support the hypothesis that objective measures of human functioning are more specific than are subjective measures.

Sedative effects of ethanol at night.

The sedative effect of 0.7 g/kg of 100% ethanol, ingested at 9:30 PM, was investigated to examine the combined effects of ethanol and circadian sleepiness/alertness levels. Fourteen healthy young adults participated in a placebo-controlled, double-blind crossover design. Each subject, on two separate occasions (placebo or ethanol), completed multiple sleep latency testing and the repeated test of sustained wakefulness as objective measures of physiological sleep tendency, and completed the Stanford Sleepiness Scale as a measure of subjective sleepiness. The results indicate that a moderate dose of ethanol significantly increases physiological sleepiness during early morning hours even in individuals that are relatively alert at these times. Therefore, the marked reduction in alertness and related performance deficits that normally occur at night are worsened by ethanol ingestion. Sleepiness, due to any cause, and ethanol may well be a dangerous combination.

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.

Transient insomnia associated with a 3-hour phase advance of sleep time and treatment with zolpidem.

A 3-hour phase advance of sleep time was employed to produce a model of transient insomnia. The degree to which this manipulation was effective varied substantially among young, healthy normal sleepers. Zolpidem, an imidazopyridine hypnotic compound, was effective in reversing the sleep disruption in those individuals displaying transient insomnia in this model.

Effect of caffeine on physiological sleep tendency and ability to sustain wakefulness at night.

Marked sleepiness occurs during typical night shift work hours and this reduced alertness is associated with marked performance deficits. The effect of caffeine (versus placebo) upon sleepiness at night was studied using objective measures of physiological sleep tendency and ability to sustain wakefulness. Both measures show caffeine to reduce sleepiness at a single dose roughly the equivalent of two to four cups of coffee. Despite impressive objective differences in alertness with caffeine, subjects did not consistently differentiate between drug conditions on subjective alertness assessments. The use of CNS stimulants to promote alertness during night shift hours should be considered, particularly for occupations for which alertness is critical.

Physiological sleep tendency on a simulated night shift: adaptation and effects of triazolam.

Daytime sleep and nocturnal sleepiness were examined in 18 normal sleepers (9 young adults, 9 middle-age adults) for 5.5 days following acute sleep/wake schedule inversion. Triazolam and placebo were compared in a counterbalanced, crossover design. Triazolam improved daytime sleep, but did not produce significant changes in sleep tendency at night. Physiological sleep tendency in the early morning hours (0200 to 0600) was profound, but decreased significantly within 3 to 4 days following sleep/wake inversion, irrespective of treatment condition. Nocturnal performance data generally were consistent with changes in physiological sleep tendency. We conclude that extending daytime sleep by an average of approximately 50 min per day via administration of a hypnotic does not appear to significantly reduce circadian sleep tendency in the early morning hours. Further, considerable adaptation, in terms of sleep tendency, occurred within a weak of simulated night shift despite a relatively constant daytime sleep pattern.

Acute administration of triazolam for the daytime sleep of rotating shift workers.

Ten rotating shift workers, who changed shifts every 1 to 4 weeks, slept in the laboratory during the first four daytime sleep periods of two consecutive tours of night shift. Prior to the first two sleep periods of one tour, the subjects were given 0.5 mg triazolam. Placebo was administered prior to sleep periods one and two of the other night shift tour. Neither drug nor placebo was given before the third and fourth sleep period of either tour of night shift. Conditions were counterbalanced among subjects. Polysomnography demonstrated that triazolam significantly increased total sleep time and sleep efficiency relative to placebo, primarily by promoting sleep maintenance. No adaptation to daytime sleep was seen during the four consecutive sleep periods without triazolam (placebo, then no drug). Triazolam did not appear to promote adaptation to daytime sleep on the 2 days following triazolam administration.