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Biomedical subjects

J Foret

Publications and source records attributed to J Foret.

At least 37 records · Page 2Linked to original sources
PubMed1988

[Circadian regulation of the sleep-wake cycle].

A review of the studies considering the sleep/wake alternation as a biological circadian cycle is presented. The methods designed to evaluate respectively the role of both the endogenous component and the external synchronizers of isolation (free-running protocols). There are mutual relations between wake/sleep cycle and some other circadian rhythms, particularly body temperature rhythm. When sleep is subjected to any time manipulation, the homeostatic regulation of some sleep characteristics (REM-sleep amount, sleep onset probability, sleep length) remains very strong. Alertness appears to be linked both to sleep characteristics and to internal temperature evolution. In addition, it proved to present some degree of independence of the two afore mentioned factors, specially when motivation and/or other psychological factors are involved. The afternoon nap, far from being simply after lunch reaction, is a normal manifestation of circadian rhythmicity.

Attention↗
PubMed1987

Early rising or delayed bedtime: which is better for a short night's sleep?

The present study compares the effects on sleep and the subsequent period of wakefulness of delaying bedtime of 2 h or advancing rising time by 2 h in subjects clearly differentiated by morningness or eveningness in their circadian rhythms. Twelve young healthy good sleepers, six morning types (MT) and six evening types (ET), were selected. The data obtained from the second 24 h (night and day) with delayed bedtime (DB) and advanced rising time (AR) were compared with those obtained in the reference condition (R) with normal sleep schedules. Sleep was recorded polygraphically and rectal temperature was continuously monitored during the nights and during the day following the second night of each condition. Subjective estimations of alertness, performance tasks and urinary steroids were analysed. Early rising appeared to be more disturbing than a late bedtime. The second shortened night showed fewer characteristics of recovery sleep in AR than in DB. The decrease in self rated alertness was a function both of the type of condition (DB or AR) and of the morning-evening typology of the subject. The largest decrease was observed in AR and in the ET subjects. AR also resulted in the most pronounced decrease in performance tasks and in an increase in urinary 17 ketosteroids without changes in the 17 hydroxy-corticosteroids. The effects on rectal temperature were limited to short periods after bedtime in DB and rising time in AR.

17-Hydroxycorticosteroids↗
PubMed1986

Diurnal variation in subjective and objective measures of sleepiness: the effects of sleep reduction and circadian type.

In young, good sleepers the diurnal evolution of alertness was studied as a function of degree of morningness: (1) during habitual sleep routine and (2) in a 2-hr sleep reduction protocol. During habitual sleep routine, alertness was assessed using both the subjective evaluation based on Thayer's Activation Deactivation Adjective Checklist (43 subjects) and the objective measurement of sleep latency (Multiple Sleep Latency Test, MSLT). Self-alertness scored highest around midday. Later it showed a dip, then stayed on a plateau until about 2200 hr. On average, 77% of the subjects fell asleep at the 1400 hr MSLT session while only 35.5% did at 1000 hr and 25.8% at 2000 hr. Morning-types (MT) and evening-types (ET) differed only during the morning: ET fell asleep more frequently at 1000 hr and 1200 hr and rated lower self-alertness on arising than did MT. Twelve subjects were given the protocol of a 2-hr sleep reduction (both in delayed bedtime and advanced rising time conditions). At 0700 hr, MT rated their alertness lower when they had only just gotten up (delayed bedtime condition) than when they had been awake for 2 hr (advanced rising time condition). In contrast, ET had the same low level of alertness at 0800 hr, independent of the time elapsed since arising. On average the advanced rising time condition affected the general pattern of alertness more than did delayed bedtime.

Adult↗
PubMed1985

Sleep and body temperature in "morning" and "evening" people.

Three groups of young, normal sleepers were selected as morning types (MTs), evening types (ETs), and neither types (NTs) as determined by the Horne and Ostberg questionnaire. Sleep and rectal temperatures were recorded under three conditions: baseline nights (Cond. 1), sleep on the recovery day after 1 night of sleep deprivation (Cond. 2), and sleep on the recovery night after 1 night and 1 day of sleep deprivation (Cond. 3). During Conds. 1 and 3, when sleep schedules were self-determined, sleep structure and body temperature were similar in MTs, and ETs, and NTs. During Cond. 2, however, MTs had poorer sleep, i.e., a smaller percentage of REM sleep and more awakenings, than ETs. This difference can be related to the evolution of temperature during Cond. 2; i.e., a temperature increase in the MT and NT and a decrease in the ET.

Adult↗
PubMed1983

The time course of slow wave sleep and REM sleep in habitual long and short sleepers: effect of prior wakefulness.

Three groups of young good sleepers were selected according to their habitual sleep length as short (SS), regular (RS), or long (LS) sleepers. Their sleep was recorded in three situations: reference nights, a recovery sleep night after 36 h of sleep deprivation, and a sleep night after a morning sleep recovery from sleep deprivation (12 h waking time). Total and cycle-by-cycle amounts of slow wave sleep (SWS) and REM sleep were studied both as a function of experimental conditions and of the group of subjects. In all three conditions, LS had less SWS than other sleepers while the differences in SWS amounts between groups were mainly due to different amounts in the second and third cycles, differences between conditions essentially due to variations of SWS within sleep cycle 1 (SWS1). SWS1 appeared to reflect some physiological process whose level increases during waking and declines during sleep. REM sleep proved to be proportional to sleep length.

Adult↗
PubMed1981

[Intra-sleep awakenings in relation to habitual sleep length and modifications of the sleep-wake rhythms (author's transl)].

The number of episodes of intervening wakefulness, their duration and their sleep stage occurrence were analyzed in the sleep recordings of 19 young (19-23 years), good sleepers. There were 5 long sleepers (LS), 5 short sleepers (SS) and 9 regular sleepers (RS). The experimental protocol included 2 reference nights, a night sleep recovery (after 36 h of wakefulness) and a day sleep recovery (after 24 h). The night following the day sleep recovery was also recorded. The duration of waking episodes was very stable and was independent both of type of sleeper and of situation. The histogram of these durations seemed to follow an exponential law. The number of awakenings varied according to the individual, the habitual sleep length (SS had very few) and the situation (such as length of prior wakefulness or circadian factors).

Adult↗
PubMed1981

Diurnal rhythm of axillary temperature in long and short sleepers: effects of sleep deprivation and sleep displacement.

Six habitual long (greater than or equal to 9 hr) sleepers (LS) and 6 habitual short (less than or equal to 6.5 hr) sleepers (SS) measured their diurnal axillary temperature (T) every 4 hr from awakening time to bedtime. For the control span of 10 days, temperature peak time was similar in both groups but occurred later in SS than in LS when measured from midsleep. Bedtime was closer to temperature peak time in LS than in SS. While experiencing the same sleep deprivations (SD 24 hr with morning sleep recovery and SD 36 hr with nocturnal sleep recovery). SS maintained a more stable body temperature curve than LS. After the nights of sleep deprivation, morning temperature increased in LS but not in SS. In both experimental conditions LS tended to advance their temperature peaks. This shift resulted in a statistically significant difference between the groups' T peaks for the 36-hour sleep deprivation. These results suggest that coupling between sleep/activity rhythm and temperature rhythm probably is different in LS and in SS, being stronger in LS.

Adult↗
PubMed1980

Habitual sleep length and patterns of recovery sleep after 24 hour and 36 hour sleep deprivation.

Five long sleepers (LS) and 5 short sleepers (SS) were selected from 310 medical students. Nine regular sleepers (RS) were used as a control. The sleep was recorded during 3 reference nights, one recovery night after a 36 h sleep deprivation (R2), one morning sleep after a 24 h sleep deprivation (D1) and the night following D1(R1). According to previous data slow wave sleep (SWS) amounts were the same in the 3 groups while stage 2 and paradoxical sleep (PS) amounts increased with the sleep duration. The hourly distribution of intervening wakefulness and SWS were similar for all groups. When compared to RS or SS the hourly distribution in LS of PS was lower until the sixth hour. As a function of experimental conditions, sleep patterns of LS were the most affected. In R2 the sleep of LS more closely resembled that of RS or SS than in reference nights, while in R1 LS' sleep was the most disturbed. Morning sleep durations were very similar for all groups, but in LS intervening wakefulness was increased and PS was decreased when compared to RS and SS. Negative correlations (Spearman rank test) were found between the morning increase of body temperature after a sleep-deprived night and both TST and PS durations. In all recorded sleep periods, SWS amounts were positively correlated with prior wakefulness duration and the PS amount with TST.

Adult↗
PubMed1980

Conversion of percutaneous ureteral stent to indwelling pigtail stent over guidewire.

A ureteral stent placed percutaneously through a nephrostomy can be readily exchanged endoscopically for a ureteral indwelling pigtail stent over a percutaneous guide wire. Percutaneous antegrade stent placement can sometimes be accomplished when retrograde placement cannot. We report 10 successful conversions to indwelling stent in 11 cases. In 1 case the percutaneous guide wire could not be retrieved endoscopically because of a bleeding tumor in the bladder. No serious difficulties or complications were encountered. The percutaneous approach offers an alternative method of providing internal urinary diversion if retrograde ureteral indwelling stent placement has failed.

Adult↗
PubMed1980

Subcutaneous implantation of percutaneous ureteral stents.

The authors describe their experience with subcutaneous implantation of percutaneous ureteral stents. Three of the five procedures were complicated by infection, urine leak and/or chronic drainage at some time during their course. One patient developed pressure changes of the skin overlying the implanted tube. The problems encountered in this initial experience are avoidable. Subcutaneous implantation of percutaneous ureteral stents can be useful in the management of appropriate patients.

Catheters, Indwelling↗
PubMed1979

Sleep onset and first cycle of sleep in human subjects: change with time of day.

The first cycle of sleep was studied in different situations: normal night sleep, naps, diurnal sleep after night shifts (3 x 8 shift workers). Results show two types of first cycle: some started with SWS (normal cycles), others with REM (sleep onset REM periods: SOREMPs). (1) Normal cycles: the length of SWS in the first cycle was positively correlated with prior wakefulness; conversely, the latency of SWS decreased as prior wakefulness increased; the decrease was due to the decrease in the length of the previous stage II or of the sleep onset latency (SOL). Length of sleep onset (SO) showed only few variations. The structure of the first cycle of shift workers' sleep probably reflects an important sleep loss. (2) SOREMPs occcurred during diurnal sleep. Some hypotheses about these cycles are discussed including REM 'pressures' (circadian, sleep loss) and inter-individual variations.

Adult↗