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Biomedical subjects

B M Stone

Publications and source records attributed to B M Stone.

At least 19 recordsLinked to original sources
PubMed1992

Sleep of Andean high altitude natives.

The structure of sleep in lowland visitors to altitudes greater than 4000 m is grossly disturbed. There are no data on sleep in long-term residents of high altitudes. This paper describes an electroencephalographic study of sleep in high altitude dwellers who were born in and are permanent residents of Cerro de Pasco in the Peruvian Andes, situated at 4330 m. Eight healthy male volunteers aged between 18 and 69 years were studied. Sleep was measured on three consecutive nights for each subject. Electroencephalographs, submental electromyographs and electro-oculograms were recorded. Only data from the third night were used in the analysis. The sleep patterns of these subjects resembled the normal sleep patterns described by others in lowlanders at sea level. There were significant amounts of slow wave sleep in the younger subjects and rapid eye movement sleep seemed unimpaired.

Adolescent↗
PubMed1991

Circadian rhythmicity and sleep of aircrew during polar schedules.

Sleep and circadian rhythms of aircrew were studied during a 7-d polar schedule operated between London and Tokyo. Sleep, rectal temperature, and subjective alertness were recorded for 2 d before departure during the schedule, and for 10 d after the return. Changes in sleep during the early part of the trip were due to sleep loss on the outward journey, but later these changes were related to the displacement of the circadian rhythm. The acrophases of the circadian rhythms of temperature were delayed by the outward journey, and amplitudes were reduced throughout the trip. During the return, aircrew reported high levels of tiredness which persisted until the second recovery night. Though the amounts of sleep obtained during the schedule were satisfactory for the aircrew as a group, some crewmembers experienced difficulties. Realignment of circadian rhythms was attained by an advance of the circadian phase in eight aircrew and by a delay in three, and resynchronization was achieved in all cases within 6 d.

Adult↗
PubMed1990

Performance and quality of sleep wearing NBC protective clothing.

Two separate studies were carried out to investigate the effect of wearing nuclear-biological-chemical aircrew equipment assembly (NBC AEA) protective clothing on performance and on overnight sleep. Performance at a series of tasks was measured, in six male subjects, during the day (0800-2000 hours) and at night (2000-0800 hours). Wearing the NBC assembly did not lead to significant decrements in performance compared with the normal aircrew equipment assembly (AEA). The sleep of six male volunteers was recorded electroencephalographically on two consecutive nights when NBC protective clothing was worn. Sleep was both shortened and disturbed, compared with overnight control sleep. There were some improvements on the second night, suggesting that individuals may adapt to wearing the NBC assembly.

Adult↗
PubMed1989

The influence of a 1 h nap on performance overnight.

The effect on performance overnight of a 1 h nap taken at 0200 h was studied in six young female subjects. The subjects completed three schedules, including one with a nap and two without a nap, during which either a placebo or 300 mg caffeine was ingested at 2315 h. Performance was measured from 1700 h in the evening until 1030 h the next morning. Caffeine improved performance overnight on almost all tasks compared with placebo. The nap had some limited beneficial effect compared with placebo, but most tasks remained impaired.

Adult↗
PubMed1988

Altitude insomnia: studies during an expedition to the Himalayas.

During an expedition to the Himalayas, we studied the sleep and respiration of six climbers. Three ingested acetazolamide (500 mg) daily throughout the climb and the other three ingested placebo. At high altitude (4,150-4,846 m), each subject ingested temazepam (10 mg) for one night and placebo for another. Acetazolamide improved sleep above 2,750 m, but it is uncertain whether this was due to sedation or to improvements in arterial oxygen saturation. Sleep was markedly disturbed in all subjects above 4,000 m. Temazepam improved sleep, and in subjects taking acetazolamide, it reduced sleep-onset latencies and increased sleep efficiency close to that of sea level values. These observations suggest that the prophylactic use of acetazolamide is likely to improve sleep in climbers and that a low dose of a benzodiazepine such as temazepam (10 mg) may be beneficial at high altitude. Studies are now needed to exclude any possibility of respiratory impairment at altitude before a firm recommendation can be made regarding the routine use of this hypnotic.

Acetazolamide↗
PubMed1987

Efficacy of zopiclone in middle age.

Effects of zopiclone (5.0, 7.5, and 10 mg) on sleep and on performance were studied in middle-aged subjects. Zopiclone (5.0-10.0 mg) reduced awake activity and the number of awakenings, and increased the duration of stage 2 sleep. The appearance of REM sleep was delayed, but this effect was without reduction over the whole night. There were no impairments in the digit symbol substitution test when zopiclone was compared with placebo, although there were less substitutions with 10.0 mg than with 5.0 mg. Symbol copying and choice reaction time were unaltered. Zopiclone would appear to be a useful hypnotic for those involved in skilled work. Based on the results obtained in healthy volunteers, the 5.0 mg dose would be appropriate for many; if in insomniac patients, 7.5 mg was needed, then it is likely to be free of undue impairment of performance the next day.

Azabicyclo Compounds↗
PubMed1986

Sleep after transmeridian flights.

Nocturnal sleep and daytime sleep latencies, recorded electroencephalographically after westward and eastward flights across the North Atlantic involving time zone shifts of 5 h, were influenced by the time of the flight and by subsequent displacement of the rest period. After the westward flight there was sleep disturbance during the latter part of the first night. However, there was persistent disturbance of sleep after the eastward flight. A rapidly eliminated hypnotic may be useful for the first night or two after a westward flight and for a few nights after an overnight eastward flight.

Adult↗
PubMed1986

Antihistamines: impaired performance and the tendency to sleep.

The central effects of various antihistamines were studied using a variety of tests of performance, including visuo-motor co-ordination and dynamic visual acuity, as well as paper and pencil tests and critical flicker fusion. The possible relationship between performance and sedation was also studied using digit symbol substitution and latencies to drowsy sleep. There was high degree of correlation between drowsiness, as indicated by the relative ease with which individuals fell asleep over the day, and impaired performance, but it was not possible to establish the relationship for each time of the day. These findings lend some support to the suggestion that impaired performance with antihistamines may be a non-specific effect of sedation.

Adult↗
PubMed1986

Modulation of catecholamine transmission and sleep in man.

The effect of modulation of catecholamine transmission on sleep in man was studied using mianserin (20 and 40 mg) and nomifensine (50 and 100 mg). It is suggested that reduced wakefulness induced by mianserin during sleep is primarily related to postsynaptic antagonism of alpha adrenoceptors, though a possible synergistic effect with antagonism of histamine H1 receptors cannot be excluded, while increased wakefulness with nomifensine is related to inhibition of the uptake of catecholamines and/or direct or indirect dopaminergic activity. The reduction in rapid eye movement (REM) sleep with both drugs is believed to be a non-specific effect which arises from a disturbance of the balance between monoaminergic and cholinergic influences.

Adult↗
PubMed1986

Hypnotics and transient insomnia.

An hypnotic should be used only when there is evidence of sleep disturbance. The wide range of sleep disorders (e.g. delayed sleep onset or problems of sleep maintenance) and the added complication that the patient may be involved subsequently in skilled work demand that the pharmacokinetics of various hypnotics must be understood before the correct hypnotic can be chosen. Impaired performance is more severe and persists far longer with compounds that are slowly eliminated and with the use of higher doses. The particular situations of aircrew and mountaineers have been studied in detail. Caution must be exercised in the management of aircrew coping with irregularity of rest and work. Temazepam has been used for aircrew for over 10 years and the absence of adverse effects ensures that it remains the recommended hypnotic in this area of medical practice. The relationship of insomnia with the hypoxic environment is undetermined. To investigate this, sleep was studied in six individuals during an expedition to the Himalayas. At altitude, temazepam led to less wakefulness and to drowsy sleep--there were no prolonged sleep latencies.

Altitude↗
PubMed1986

Irregularity of rest and activity: studies on circadian rhythmicity in man.

1. Rectal temperature, electrolyte excretion and performance were studied in young adults who followed an irregular pattern of work and rest for 9 days in an isolation unit. 2. In the analysis, effects evoked by the pattern of work and rest were separated from the oscillatory component, and rhythms for individual days were examined by the cosinor method. 3. During the schedule, rhythms no longer showed a period of exactly 24 h, and this effect was confirmed by studies using a repeated cycle of irregular work and rest and by studies using constant routines. 4. Temperature and urinary constituents differed in the strength and phase of their rhythms when corrected for evoked effects, as well as in the strength of the evoked effects themselves. 5. There was evidence of deterioration in performance during work periods which exceeded 9 h, but there was no evidence of progressive deterioration in performance over the 9 day schedule.

Activity Cycles↗
PubMed1986

Nocturnal sleep and daytime alertness of aircrew after transmeridian flights.

The nocturnal sleep and daytime alertness of aircrew were studied by electroencephalography and the multiple sleep latency test. After a transmeridian flight from London to San Francisco, sleep onset was faster and, although there was increased wakefulness during the second half of the night, sleep duration and efficiency over the whole night were not changed. The progressive decrease in sleep latencies observed normally in the multiple sleep latency test during the morning continued throughout the day after arrival. Of the 13 subjects, 12 took a nap of around 1-h duration in the afternoon preceding the return flight. These naps would have been encouraged by the drowsiness at this time and facilitated by the departure of the aircraft being scheduled during the early evening. An early evening departure had the further advantage that the circadian increase in vigilance expected during the early part of the day would occur during the latter part of the return flight.

Adult↗
PubMed1985

Histaminergic systems and sleep. Studies in man with H1 and H2 antagonists.

Effects of H1 (mepyramine, mequitazine, triprolidine and brompheniramine) and H2 (cimetidine and ranitidine) antagonists on sleep were studied in healthy man. There were no effects of mepyramine (50 and 100 mg), and the only effect of mequitazine (5 and 10 mg) was a reduction in the number of awakenings. Triprolidine (10 and 20 mg) and brompheniramine (4 and 8 mg) did not alter wakefulness during sleep or the total sleep time, but rapid eye movement sleep was reduced. There were no effects of ranitidine (150 and 300 mg), but slow wave sleep was increased by cimetidine (200 and 400 mg). It is tentatively suggested that the histaminergic system is concerned with the mechanisms which favour vigilance during the wakeful state, and the balance between wakefulness and slow wave activity during sleep. Effects of some H1 antihistamines on rapid eye movement sleep are believed to be due to their monoaminergic rather than their histaminergic activity.

Adolescent↗
PubMed1985

Central effects during the continuous osmotic infusion of a benzodiazepine (triazolam).

The effects of relatively constant plasma levels of a rapidly eliminated benzodiazepine (triazolam) were studied in young healthy males to determine whether tolerance to certain effects may develop over a relatively short period of time. The drug was given over a period of 30 h (2 days and 1 night) at zero-order rate using a rectal osmotic pump. Performance was measured at 2 hourly intervals during the day and was continuously impaired during the infusion, though there was a rapid recovery when the infusion ceased. All tasks were affected, in particular mental arithmetic and letter cancellation, but there was some improvement in performance during the second day. The normal circadian improvement in performance may have contributed to this effect, but some degree of tolerance to the effect of the drug cannot be excluded. Overnight there was a marked reduction in wakefulness, suppression of slow wave sleep, and delay to the onset and reduction in the duration of rapid eye movement sleep. During the night after infusion there was less slow wave sleep and increased wakefulness. The experimental design may prove useful in the study of tolerance to drugs.

Adult↗
PubMed1985

Sustained performance with short evening and morning sleeps.

The effect which early evening sleep may have on overnight and subsequent daytime performance, and the effect which morning sleep may have on daytime performance after overnight sleep deprivation has been studied in six healthy male volunteers. It would appear that relatively short periods of natural and drug induced (brotizolam 0.125 mg) sleep have a beneficial effect on subsequent performance even in the absence of preceding sleep debt. In the event of disturbed sleep in shiftwork an hypnotic may be helpful, and in this context, one which is rapidly eliminated and sustains sleep is appropriate.

Adult↗
PubMed1985

Hypnotics and aircrew.

The management of sleep difficulties which arise during air operations must be related, at least initially, to the cause, but the aeromedical specialist is frequently faced with the possible use of hypnotics. There are no simple guidelines, but an understanding of various issues will help toward the effective use of these drugs in those who have to cope with irregularity of rest and carry out skilled work. Some knowledge of the pharmacokinetics of the drugs concerned is useful as persistence of effect and the potential for accumulation with repeated ingestion are important factors, while efficacy in relation to sleep of different durations and at unusual times must also be considered.

Adult↗
PubMed1984

Ascorbic acid and performance in man.

Effects on performance of 1, 2 and 4 g ascorbic acid were studied from 0.5-5.5 h after ingestion in six healthy females. Diazepam (5 mg) was included as an active control, and it impaired digit symbol substitution, visuomotor coordination and complex reaction time. There were no effects of any dose of ascorbic acid on performance.

Adult↗