Showing papers by "Peretz Lavie published in 1989"

Twenty-four-hour structure of sleepiness in morning and evening persons investigated by ultrashort sleep-wake cycle.

Abstract: "Morning" and "evening" persons, defined according to a modified version of the Horne and Ostberg questionnaire, performed the 7/13 min sleep-waking schedule under attempting sleep condition after sleeping for one night in the laboratory, and under the resisting sleep condition after one night of sleep deprivation. Morning types slept significantly more under the attempting sleep condition and showed an earlier rise in nocturnal sleepiness. After sleep deprivation, morning types had a more distinct sleep propensity pattern with well-defined midafternoon and nocturnal sleep gates. In this condition there was a significant interaction between type and time of day with respect to amount of sleep: morning types slept more during the night, and evening types slept more during the day. Based on their amounts of sleep, subjects were also divided into "sleepy" and "alert" types, which were independent from the chronotypology.

Ultradian rhythms in arousal--the problem of masking.

Abstract: Studies utilizing widely different experimental techniques provided evidence that there are spontaneous ultradian cycles in arousal during the waking state. These comprised of cyclic fluctuations between increased and decreased sleep propensity with a periodicity of about 1.5 hr. Being of relatively low amplitude, these cycles are vulnerable to masking effects by a variety of experimental conditions. Masking can be exerted by varying the tonic level of arousal, by coexisting slow ultradian components which are particularly prominent during the second half of the day, or by some specific experimental conditions. Furthermore, increased sleepiness was shown to enhance the slow ultradian components and suppress the 1.5-hr cycles in EEG indices of arousal on the one hand, and to emphasize the 1.5-hr cycles in motor activity and reaction time performance on the other hand. Much more attention should be paid to the problem of masking of ultradian cycles in arousal. Recognizing the sources and reasons for masking will advance our knowledge of the characteristics of these cycles and their function.

Sleep disturbances in shift-workers: a marker for maladaptation syndrome

Abstract: The present study investigates the association between sleep disturbances in shift workers and their general adaptation to the shift system. Three hundred and sixteen refinery, and 55 aluminium factory shift-workers participated in this study. In both plants, sleep disturbances were significantly associated with age, with dissatisfaction with working conditions and the quality of domestic life, with increased morbidity and increased high blood pressure. The association between high blood pressure and morbidity and sleep disturbances remained significant after adjusting for age. Shift workers complaining about their sleep also had higher blood pressure values than day workers with sleep disturbances. These findings suggest that periodic evaluation of sleep quality in rotating shift workers can provide useful information regarding their general adaptation level to the shift system.

Motor abnormalities during sleep in patients with childhood hereditary progressive dystonia, and their unaffected family members.

Abstract: The structure of sleep and number of body movements (BMS) and periodic leg movements during sleep (PMS), were studied in three unrelated girls suffering from L-DOPA responsive hereditary dystonia with marked diurnal fluctuation and in their 11 healthy, close relatives. All three girls had an increased number of BMS during rapid eye movement (REM) sleep. Five of the six parents and three siblings had abnormal PMS. One pair of parents had BMS similar to those of their affected daughter. The occurrence of BMS and PMS in the families studied may indicate a common mechanism for both. Because familial PMS is quite rare in its pure form, and this type of dystonia is also rarely encountered, the occurrence of BMS and PMS in members of these families may imply a causative relation between these two sleep-related motor phenomena.

Intrinsic effects of the benzodiazepine receptor antagonist RO 15-1788 in sleepy and alert subjects.

Abstract: The present paper investigated the differential effects of 5 mg, 60 mg and 120 mg of the benzodiazepine receptor antagonist RO 15-1788 on the ability to resist sleep of sleepy and alert subjects. Repeated administrations of 5 mg potentiated the hypnotic effects of sleep-deprivation in alert subjects and decreased the hypnotic effects in sleepy subjects. Similar differential effects were found with respect to two factors of subjective mood. The two higher levels of the drug decreased sleepiness more in sleepy than in alert subjects. These results are interpreted to support the hypothesis that the effects of RO 15-1788 may be dependent on the level of an endogenous benzodiazepine-like sleep factor.

Twenty-Four Hour Patterns of Sleep Propensity

Abstract: Recent years have seen a growing number of studies demonstrating the existence of ultradian cycles in various indices of arousal with periodicities centered at around 1.5h, 3–5h, and perhaps also at 12h. The present paper describes our studies on ultradian variations in arousal utilizing an ultrashort sleep-wake paradigm. The following picture of spontaneous variations in arousal emerged from the results of these studies: There are three distinct windows during the course of the 24 hrs characterized by spontaneous variations in sleep propensity: the midafternoon increase in sleepiness, an early evening period of decreased sleep propensity (“forbidden zone for sleep”) and a gradual step-like nocturnal increase in sleepiness. This structure remained unchanged under sleep deprivation except for the nocturnal increase in sleepiness, which was modified into a sudden ‘one-trial’ increase in sleepiness. This latter phase was termed the ‘primary’ or nocturnal ‘gate’ for sleep. The timing of the nocturnal ‘gate’ was shown to be a stable individual characteristic. Implications of these findings to theories on sleep-wake regulation are discussed.