E.E.G. tracings during sleep were compared in three age groups: 20-30 years, 50-60 years and 60-70 years. There was a marked reduction in stages 3 and 4 as a function of age, an increase in awakenings during the night and in stage I, and a considerable modification in temporal distribution of PS during the night, this being no longer more concentrated at the end of the night but tending to be regularly distributed throughout the night period. The authors emphasize that sleep organization persists in normal subjects up to an advanced age. The average effects of aging (reduction in SWS and increase in awake periods and light sleep) do not necessarily reflect changes occurring in sleep in any given individual. A hypothesis is suggested that the effects of aging rather tend to produce an increase in certain individual sleep characteristics.

Adult↗

PubMedDate not supplied

Effects of age, working hours, and job content on sleep: a pilot study.

The effects of age, shiftwork with changing schedules, and job stress on self-reported sleep quality were studied in 2767 wage earners aged 32, 42, and 52, by means of a questionnaire. Greater age was associated with poorer sleep quality, as was shiftwork for the 32- and 42-year-olds but not for the 52-year-olds, suggesting a selection effect between the ages of 42 and 52. More than specific job demands, it was perceived job difficulty that was related to sleep dissatisfaction. No interactions between age, shiftwork, and job characteristics were found.

Adult↗

PubMedDate not supplied

Bright light during nighttime: effects on the circadian regulation of alertness and performance.

The present studies evaluated to what extent duration (all-night or 4-hour exposures) and timing of nocturnal bright light (BL) (beginning or end of the night) modulate effects on vigilance. The results showed that all-night BL exposure is able to alleviate the nocturnal decrements in alertness and performance. However, under certain circumstances, this continuous BL exposure may induce adverse effects on mood and finally reveal to be counterproductive. Shorter BL exposure (4 h) during nighttime helps improve mood and performance, although the effects of short BL pulses were less efficacious than all-night BL exposure. The latter part of the night appears the best time for using the alerting effect of BL. The immediate alerting effect of BL seems to be mediated by a global activation of the central nervous system.

Adult↗

PubMedDate not supplied

Binaural record of cochlear potentials in the guinea-pig and directional hearing.

Explore the source record for details and available documents.

Action Potentials↗

PubMedDate not supplied

Circadian rhythms (temperature, heart rate, vigilance, mood) of short and long sleepers: effects of sleep deprivation.

Seven long sleepers (LS) (sleep greater than or equal to 9 h) and seven short sleepers (SS) (sleep less than or equal to 7 h), aged 20 to 23 years, were selected among medical students. They measured their axillary temperature (T), heart rate (HR) and self-estimated their vigilance (V) and mood (M) every 4 h from awakening to bed time during a ten-day control span and during the two sleep deprived nights. Polygraphic sleep recordings were performed on 3 control days and recovery from 24 h (day sleep) or 36 h (night sleep) sleep deprivations. For the 4 variables (T, HR, V and M), group circadian patterns were analyzed by means of the cosinor method for the control span and after both types of sleep deprivation. The acrophases of the 4 variables clustered more in LS than in SS. The acrophases of V and M were found to be more closely related to the sleep/wake rhythm than those of T and HR. Sleep deprivation resulted in a large change of the circadian rhythms in LS but had little effect in SS as indicated by the non detection of most acrophases in LS and the persistence of such acrophases in SS. This difference might be explained by the large interindividual variability of changes induced by the sleep deprivation in LS. Moreover, day sleep recovery was more disturbed in LS than in SS.

Adult↗