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The interest in studying the brain electrical activity as a function of the development of intelligence has been spurred by the need to understand how the brain responds to environmental information. The description of sleep in mentally retarded children reveals deviant patterns of the EEG-spindles and of the eye movement activity (REM sleep) when compared to normal children. The patterns may be considered as a valuable index of mental function. According to experimental evidence, the distribution of the eye movements of sleep appears either as random or ordered. The latter are altered in the mentally handicapped in whom the appearance out of chaos, of the order which is needed for intelligence and memory to function, is altered. The sleep signs are redundant as from birth. Their pattern is also related to the psychomotor development of the infant. If their distribution remains random, or appears in long uninterrupted sequences of waves as in epilepsy, intelligence does not develop. A similar strategy appears to function in the foetus when nature organizes the structures that will lead to the development of intelligence. The eye movement patterns of sleep change in the pregnant women as a function of term and resemble those of premature babies of a similar gestational age. They also change as a function of the menstrual cycle and more generally as a function of age. The hypothesis that attention is the diurnal equivalent of REM sleep is discussed. Attempts at modelling the eye movement patterns of REM sleep as a function of near zero gravity environments have been made. 1) By means of a Montecarlo simulation using the semi Markov model during the Spacelab 1 flight. 2) With the method of the single and multiple g-phase transition analysis of the strange attractor dimension (d) during parabolic flights. The implication of the latter for the neural processes involved in learning is that the central nervous system can preserve intact, from input to output, over a period of several days, all the information it receives 3) The relation between spindles and eye movements has also been viewed by a quantum approach which is another medium between the information and the way of describing it.

The measurement of the influence of different gravity levels on the brain allows to explain how humans react to microgravity in space and to predict the adaptation capability of astronauts. Human electroencephalographic (EEG) signals were recorded during low and high gravity phases of three consecutive days of parabolic flights on the Caravelle aircraft in 1991. EEG signals were processed, using the method of correlation dimensions d of chaotic strange attractors. Results show clear differences between the three flights, with a general decrease over time in the attractor dimensions, a measure of the brain response to changing g levels. However, the dimension is not a one-to-one relation with g levels, as additional variations are observed. Two hypotheses are introduced, the "fatigue/stress" and the "g stress" hypotheses corresponding, respectively, to long-term fatigue accumulated over the three flights, and to short-term fatigue in response to change in g levels. The former explains the overall decrease of dimensions, the latter yields additional variations on shorter time scales. As the brain response degrades with time, at least six degraded modes were observed, explained by both short- and long-term fatigue., (c2002 Elsevier Science Ltd. All rights reserved.)

A remote computerized health care (telehygiene) system for space travel includes monitoring devices and pharmaceuticals aimed at the optimization of health and the environment. Early risk indicators are provided by dynamic characteristics of rhythms of several frequencies describing variation inside the physiologic range. These rhythm characteristics, assessed as one goes, can be updated and compacted as data accumulate by the use of chronobiologic software that resolves anticipated components of lower and lower frequency, thus providing summaries of data at intervals of differing length. At any time, harbingers of risk, including characteristics of circannual rhythms, can be retrieved in an instant. On their basis, early preventive action can be instituted for risk lowering and for delivery of timed treatment when needed. Preventive or curative health care in space and terrestrial spin-offs are the more effective the more of the chronome (time-structure) is resolved.

Zopiclone is a new nonbenzodiazepine hypnotic, the recommended dose of which is 7.5 mg. It was compared to flurazepam 30 mg in a sleep laboratory study. 12 women aged 40-60 years, with subjective sleep disorders for at least 2 months, were treated for 13 nights with each drug in a crossover double-blind design. Each active drug period was preceded by 5 days of placebo washout and followed by 35 days of withdrawal (no treatment). A baseline period of 4 nights (without treatment) was obtained before the study itself. The subjects slept in the sleep laboratory during the baseline period, during the last 3 nights on placebo, during the last 3 nights on active drug, and from the 11th to the 13th night after active drug discontinuation. Polygraphic recordings were obtained during each of these nights. The criteria of Kales and Rechtschaffen were used to score the tracings. Both drugs were shown to be effective when compared to placebo. Comparisons between the two periods with active treatment did not show significant differences for sleep onset latency, total sleep time, sleep efficiency index, stage 0, percent REM, number of REM periods, and REM latency. There was a trend towards an increase with zopiclone of the number of awakenings, percent of stage 3, percent of deep sleep, and an increase with flurazepam of the percent of light sleep. A significant difference was only found for percent of stage 2 (increased with flurazepam).

The operational value of measuring paradoxical sleep (PS) as a percentage of total sleeping time has been questioned. The purpose of this study was to determine the interactions between the variations in hormonal secretions and paradoxical sleep in women of different age-groups. Three parameters were utilized: REM-percent, REM-density and the eye movement frequencies. The distribution of the time-intervals between the oculomotor signals as indicated by the ratio of the higher to the lower eye movement frequencies gives a clue as to the significance of the spatio-temporal organization of the brain-signals during paradoxical sleep. This notion introduces an internal temporal and dynamic dimension in the concept of REM or Paradoxical Sleep. From our results it appears that the changes in the ratio between the different types of oculomotor discharges are a function not only of hormonal fluctuations but also of age. This point of view opens a new possibility of interpreting the results.

The study of the REM-process by means of the oculomotor frequencies has shown that it is a stochastic point process. Therefore, the techniques utilized to quantify the time-dependency of this process were used. The structure of occurrence of REM's quantified by transition probability matrixes evidenced a two-state first order semi-Markov process. The oculo-motor configurations of REM-sleep revealed two independent entities, their number and their relative frequencies. This conclusion was used as a working hypothesis for the Spacelab 1 sleep-recording experiment in zero-gravity. The results confirmed the underlying hypothesis.

The Temiars are a tribe of negroid pygmies of basically Proto-Malaysian affinities. Field-work in the Malaysian jungle provided some observations on the sleep-wakefulness cycle of two young Temiar adults. This cycle was monophasic circumstances permitting. Their rest-activity cycle at night was similar in the jungle and in the laboratory. Polygraphic total night-sleep recordings were made with both of them in the EEG laboratory in the Hospital Besar in Kuala Lumpur. The eye-movement frequencies of PS were compared with those from young adults of the West. Although the differences were not statistically significant, the Rem-densities of the Temiars were constantly at the low side. The significance of the results are being discussed.

Zopiclone is a new nonbenzodiazepine hypnotic, the recommended dose of which is 7.5 mg. It was compared to flurazepam 30 mg in a sleep laboratory study. 12 women aged 40-60 years, with subjective sleep disorders for at least 2 months, were treated for 13 nights with each drug in a crossover double-blind design. Each active drug period was preceded by 5 days of placebo washout and followed by 35 days of withdrawal (no treatment). A baseline period of 4 nights (without treatment) was obtained before the study itself. The subjects slept in the sleep laboratory during the baseline period, during the last 3 nights on placebo, during the last 3 nights on active drug, and from the 11th to the 13th night after active drug discontinuation. Polygraphic recordings were obtained during each of these nights. The criteria of Kales and Rechtschaffen were used to score the tracings. Both drugs were shown to be effective when compared to placebo. Comparisons between the two periods with active treatment did not show significant differences for sleep onset latency, total sleep time, sleep efficiency index, stage 0, percent REM, number of REM periods, and REM latency. There was a trend towards an increase with zopiclone of the number of awakenings, percent of stage 3, percent of deep sleep, and an increase with flurazepam of the percent of light sleep. A significant difference was only found for percent of stage 2 (increased with flurazepam).