Biomedical subjects

A Daurat

Publications and source records attributed to A Daurat.

10 recordsLinked to original sources

PubMed2000

Effects of zopiclone on the rest/activity rhythm after a westward flight across five time zones.

The effects of zopiclone on the rest/activity rhythm were investigated after a westward flight with a 5-h phase delay (Grenoble-Martinique). The rest/activity rhythm was recorded continuously with an actigraph monitor during a 6-day baseline episode in Grenoble and a 6-day sojourn in Martinique. Rectal temperature was recorded before the flight on day 2 and after the flight on days 2 and 5. Subjective jet-lag score was assessed before the flight on days 1 and 2 and in Martinique on days 1, 2, 5 and 6. Zopiclone (7.5 mg) or placebo were administered double blind 30 min prior to bedtime during the first 4 post-flight days (D1-D4). Under zopiclone treatment, sleep was less fragmented on the first post-flight night and the curtailment of sleep duration observed on D2 and D3 under placebo was prevented. During day-time, subjects tended to be more active than with placebo. By contrast, subjective jet-lag scores did not differ between both groups. Zopiclone seemed to accelerate the readjustment of the rest/activity rhythm and the normalisation of the phase relationship between sleep and the temperature rhythm. Zopiclone probably exerts its "resetting" effects on jet-lag desynchronosis by facilitating sleep induction rather than via a chronobiotic action.

Analysis of Variance↗

PubMed2000

Slow (0.7-2 Hz) and fast (2-4 Hz) delta components are differently correlated to theta, alpha and beta frequency bands during NREM sleep.

OBJECTIVES: Spectral power of 40 all-night sleep EEGs (Cz-Pz bipolar lead) recorded in 20 healthy young subjects was calculated after normalization on 30-s consecutive epochs by means of an autocorrelation method based on a 15-order autoregressive model. METHODS: The spectral parameters were calculated for the 7 main EEG bands: slow delta (0.7-2 Hz); fast delta (2-4 Hz); theta (4-8 Hz); alpha (8-12 Hz); sigma (12-16 Hz); beta1 (16-35 Hz); and beta 2 (>35 Hz). RESULTS: Strong negative correlations were found between power in the fast delta and either the alpha or the beta bands and between slow delta and theta bands, whereas the two delta bands showed little correlation with each other. CONCLUSION: The possibility that theses different relationships of slow and fast delta components with other frequency bands might reflect the neocortical or the thalamocortical origin of the delta waves is discussed.

Adult↗

PubMed1998

Effect of bright light at night on core temperature, subjective alertness and performance as a function of exposure time.

OBJECTIVES: This simulated night shift study measured the effects of moderate bright light (a 4-hour pulse starting at 2000 or 0400) during the exposure night and subsequent night (dim light). METHODS: Eight young males remained confined with little physical activity to a laboratory in groups of 4. After a night of reference, they were active for 24 hours; then after a morning recovery sleep, they were active again for 16 hours. RESULTS: Continuously measured rectal temperature proved to be immediately sensitive to 4 hours of bright light, particularly when given at the end of the night. Self-assessed alertness and also performance on a task with a high requirement for short-term memory were improved by the exposure to bright light. During the subsequent night the subjects were exposed only to dim light. Core temperature, subjective alertness and performance continued to show a time course depending on the preceding bright light exposure. CONCLUSIONS: Probably because evening exposure to bright light and morning sleep both had a phase-delaying effect, the effects on the circadian pacemaker were more pronounced. Thus, for practical applications in long night shifts, bright light can be considered to improve mood and alertness immediately but the possibility of modifying the circadian "clock" during subsequent nights should be taken into consideration, in particular after exposure to bright light in the evening.

Adult↗

PubMed1997

Disruption of sleep recovery after 36 hours of exposure to moderately bright light.

Eight young adults were exposed to either 36 hours of moderate bright light (BL; 1,000-2,000 lux) or a light/dark cycle (L/D < 50 lux) during constant routine. Sleep was recorded on the two subsequent recovery sleeps (R1 and R2) and compared to baseline. After the BL exposure, the rebound of stage 4 sleep and slow wave activity (SWA) were split over R1 and R2, whereas after the L/D cycle, the stage 4 sleep debt was almost completely compensated for during R1. During R1, stage 2 sleep and wakefulness accumulated faster in the BL condition than in the L/D condition. An elevation of the temperature level was also found during R1 of the BL condition. No differences between light conditions were found in urinary levels of melatonin or cortisol secreted during R1 or R2. Homeostasic process does not appear to be affected by the BL condition. A modification in the sleep-wake balance and a change in the temporal relationship between the circadian system and the sleep-wake cycle are discussed.

Adult↗

PubMed1996

Detrimental influence of bright light exposure on alertness, performance, and mood in the early morning.

The aim of this study was to assess the effects of exposure for one night to moderate bright light (BL) on subjective and objective measures of alertness, performance, and mood. Eight subjects were exposed to either BL or dim light (DL) during one night. During the previous day, they were exposed to bright light in both experimental conditions. Nocturnal BL suppressed melatonin secretion and increased body temperature. The ability to stay awake during the night, as measured by the power density in the alpha band, was significantly improved by BL exposure. BL also improved subjective alertness and performance during the first part of the night. However, improvements in the last two variables were followed by marked disruption in early morning patterns, with deterioration of mood and motivation.

Adult↗

PubMed1996

The effect on body temperature and melatonin of a 39-h constant routine with two different light levels at nighttime.

Eight healthy subjects were studied during 39-h spans (from 07:00 on one day until 22:00 the second) in which they remained awake. During one experiment, subjects were exposed to 100 lux of light between 18:00 and 8:00, and during a second experiment, they were exposed to 1000 lux during the same time span. Throughout the daytime period, they were exposed to normal daylight (1500 lux or more). The nighttime 1000-lux light treatment suppressed the melatonin metabolite aMT6s, while the 100 lux treatment did not. On the treatment day, the 1000 lux, in comparison to the 100 lux, light treatment resulted in both an elevated temperature minimum and a delay in its clock-time occurrence overnight. No real circadian phase shift in the temperature, urinary melatonin, or cortisol rhythms was detected after light treatment. This study confirmed that nocturnal exposure to lower light intensities is capable of modifying circadian variables more than previously estimated. The immediate effects of all-night light treatment are essentially not different from those of evening light. This may be important if bright light is used to improve alertness of night workers. Whether subsequent daytime alertness and sleep recovery are affected by the protocol used in our study remains to be determined.

Adult↗

PubMed1993

Temperature drop and sleep: testing the contribution of SWS in keeping cool.

Sleep and body temperature characteristics were studied in man in baseline (B), 24 h-constant routine (CR) and recovery (R) after the CR. The sleep advanced and deepened the trough of the minimum temperature when compared with CR. No relevant difference in minimum body temperature, or in the slope of temperature decrease was found, however, between B and R sleeping nights. No correlation was found between the amount of slow wave sleep and body cooling. The results do not support a homeostatic role of slow wave sleep in brain and/or body cooling.

Adult↗

PubMed1993

Bright light affects alertness and performance rhythms during a 24-h constant routine.

The aim of the present study was to assess the stimulating effects of bright light (BL) on subjective and objective alertness. Eight subjects were exposed to either bright light or dim light (DL) during a 24-h constant routine (0900-0900). Bright light failed to modify either the 24-h course or the level of body temperature. Compared to DL, BL delayed the circadian trough of motor activity by 2 h. During the night, relative to the dim-light condition, BL significantly increased subjective and objective (EEG test) alertness and improved performances. Thus, BL exposure partly counteracted the effects of sleep deprivation and/or the circadian trough on alertness and performances. During the day, BL only improved the mood and motivation levels. However, the time course of mood and motivation was not affected by the BL exposure, a nocturnal circadian trough occurring at 0630 in both light conditions.

Arousal↗

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

[French translation of Schalling-Sifneos Personality Scale Revised and Beth Israel Questionnaire, 2 evaluation tools of alexithymia].

The concept of alexithymia was first proposed in the 1960's by Sifneos and Nemiah to describe personality traits originally found in psychosomatic patients but which have since been found in other types of patients (alcoholics, drug addicts, traumatic stress disorder patients, sociopaths) as well as in the general population. Etymologically, alexithymia signifies: incapacity to speak one's emotions (from the Greek: a, lack; lexis, word; thymos, sentiments). Alexithymia is not the impossibility of feeling one's emotions, but rather the impossibility of associating them with corresponding mental representations and thus verbalizing them. Such patients tend to act out, to speak circumstantially, and to have difficulty in relationships. A neurophysiological substratum, the absence of connexions between the limbic system and the neo-cortical regions, has been suggested by Sifneos, who has distinguished primary and secondary alexithymia. A "biological" deficit seems to be responsible for primary alexithymia, such as in found in split-brain patients or aprosodias in patients with right hemispheric strokes. Secondary alexithymia, on the other hand, seems to be due to psychodynamic factors such as massive utilisation of defense mechanisms like denial, repression and regression. Appropriate psychotherapy for such patients is debatable, but it seems that in most cases the analytical approach should be replaced by more directive therapies, including relaxation and bio-feedback, to help patients learn to stimulate, master, and verbalize their emotions. The Beth Israel Questionnaire (BIQ) is a rating scale evaluating such traits that is filled out by the rater based on a clinical interview.(ABSTRACT TRUNCATED AT 250 WORDS)

Affective Symptoms↗