Sleep duration and chronotype in adults in Côte d'Ivoire: influence of gender,religion and age

This study investigated the sleep-wake rhythm and chronotype of people living in Côte d'Ivoire. We assessed sleep-wake behaviour in 556 adults (336 men, 220 women) between 25 and 54 years (mean: 38.63) by means of structured interviews. Data were analysed by linear models with sleep wake variables as dependent variables and age, gender, religion and region (urban/rural) as fixed factors controlling for number of working hours and children. Results suggest sleep length not to differ between weekdays and weekends but sleep timing (chronotype) was later on weekends with a midpoint of sleep at 1:37am during weekdays compared to 1:58am on weekends. The more children, the earlier was the midpoint of sleep and the shorter was sleep length. Midpoint of sleep was earlier in older people. Women slept longer during weekdays and were earlier chronotypes. Sleep duration was longer in the rural areas and midpoint of sleep was later in the urban areas on weekdays and on the weekend. Muslims showed the shortest sleep duration and were earliest chronotypes. Sleep-wake cycles in the African setting sample were shorter for women, Moslems, and older people.     

Author's response

The year 1996 was regarded by a considerable part of contemporary literature on global political economy as a definite turning point in modern history. The majority of experts tended to see the starting point of take‐off that year, but others—not a negligible minority—saw omens of disastrous recession and lasting depression. It appears the time has not yet come. The question is now that of the incalculable resultant of runaway (deregulated) forces of the international financial “whirlpool”, of a random process of global, regional and local accumulation of capital. The year 1997 will set in with a foreseeable and calculable agrarian and related cycle and it may find an outlet for accumulated tensions of capital accumulation at the high tide of unemployment (demographic or migratory) wave with unforeseeable and incalculable effects and side‐effects. This will be just the beginning of the end and a Black Weekday still lies ahead of us. There can be no doubt that we live in a transition period but we do not know where this transition leads to. Loose talk about “post‐industrial society”, “post‐modern age” and “postsomething anything” has limited interpretative power. Very few students of social sciences venture to see and verify secular trends in world history.     

Using paired-choice assessment to identify variables maintaining sleep problems in a child with severe disabilities

In this study, we used a paired-choice assessment protocol to identify the relative reinforcing value of stimuli and activities for a child with severe disabilities when she failed to settle to sleep at night. The results of this assessment indicated that the child preferred the mother's attention relative to other activities presented. Assessment results were incorporated into an intervention, that produced a reduction in sleep disturbance that was maintained at a 12-month follow up.     

Dichotic listening and sleep deprivation: vigilance effects

Twelve sleep-deprived and 13 non-deprived Navy cadets were tested with the dichotic listening procedure for effects of sleep deprivation on hemispheric asymmetry and sustained attention. Consonant-vowel syllables were presented to the subjects in three different conditions, a divided (non-forced) attention condition, a forced right ear and a forced left ear attention condition. In the two forced attention conditions the subjects were instructed to focus attention only on the right or left ear stimulus. The results showed an expected right ear advantage for both groups during the non-forced and forced right attention conditions, indicating superior left hemisphere processing. During the forced left attention condition, the sleep-deprived subjects showed no ear advantage at all, while the non-deprived subjects showed an expected left ear advantage. The results are discussed within a theoretical framework of a dual process model, where sleep deprivation disrupts the ability to sustain attention, caused by a temporary failure of the right hemisphere's top-down (instruction-driven) processing to override the left hemisphere's bottom-up (stimulus-driven) processing.     

Prospective Longitudinal Associations Between Persistent Sleep Problems in Childhood and Anxiety and Depression Disorders in Adulthood

The objective of this study was to examine the associations between persistent childhood sleep problems and adulthood anxiety and depression. Parents of 943 children (52% male) participating in the Dunedin Multidisciplinary Health and Development Study provided information on their childrens sleep and internalizing problems at ages 5, 7, and 9 years. When the participants were 21 and 26 years, adult anxiety and depression were diagnosed using a standardized diagnostic interview. After controlling for childhood internalizing problems, sex, and socioeconomic status, persistent sleep problems in childhood predicted adulthood anxiety disorders (OR (95% CI) = 1.60 (1.05–2.45), p = .030) but not depressive disorders (OR (95% CI) = .99 (.63–1.56), p = .959). Persistent sleep problems in childhood may be an early risk indicator of anxiety in adulthood.     

Variable-interval reinforcement schedule value influences responding following REM sleep deprivation

The effects of rapid-eye movement sleep deprivation (REMSD) in rats were studied in relation to variable-interval (VI) reinforcement schedule value. Initially, lever pressing was maintained on a VI 30-s schedule of food pellet delivery. After a baseline was established, rats were repeatedly exposed to 96 hr of REMSD and control conditions of an equivalent duration. Responding decreased following REMSD but not after exposure to control conditions. Lever pressing was then maintained on a VI 15-s schedule of food pellet delivery and exposure to the REMSD and control conditions was repeated. Under this condition following repeated REMSD exposures, rates of lever pressing became similar to baseline responding. A VI 30-s schedule of food pellet delivery was then reinstated and REMSD and control conditions were repeated. Lever pressing following exposure to the REMSD condition decreased for 3 of 4 rats. Results suggest that VI schedule value influences the effects of REMSD on responding.     

Possible contribution of better maternal psychological well-being to the acquisition of sleeping through the night in infants during the early postpartum period

The objective of this study was to elucidate whether better maternal psychological well-being contributes to the acquisition of “sleeping through the night” (STN) in infants during the early postpartum period. Fifty-two primiparous mothers completed the General Health Questionnaire-28 (GHQ-28) in the third trimester (prenatal) and when the conceptional ages of their babies reached 8–9 weeks (hereafter, 2 months), 12–13 weeks (3 months), and 16–17 weeks (4 months). They also recorded babies’ nocturnal sleep patterns in a timetable for 5 consecutive days each month postpartum. “Regular STN” was defined when the mean of longest nocturnal sleep duration for 5 consecutive days was > 8 h or between 6 and 8 h with < 1.0 nocturnal awakenings. According to these criteria, a total of 14 infants (27 %) acquired regular STN at 4 months (referred to as “STN infants”), with STN infants showing a marked increase in longest nocturnal sleep duration and a decrease in nocturnal awakenings from 2 to 3 months of age. The mothers of STN infants demonstrated steady reductions in postnatal GHQ-28 scores and had significantly lower prenatal GHQ-28 scores compared with the mothers of non-STN infants (3.7 ± 3.0 vs. 6.4 ± 4.1, p = 0.027). In random forest models for binomial classification, both prenatal and postnatal (at 4 months) GHQ-28 scores were identified as significant covariates for distinguishing STN infants, and other important covariates, including weeks of delivery, stepfamily, birth weight of the infant, and maternal co-sleeping at bedtime, were selected. Among these covariates, maternal co-sleeping at bedtime had relatively stronger correlations with both STN infants (r = − 0.440) and prenatal maternal GHQ-28 scores (r = 0.377). In conclusion, because prenatal maternal psychological well-being was thought to predict the acquisition of STN in infants, infants born from mothers with better psychological well-being appear to have some advantages in acquiring STN. These cross-lagged correlations suggest that the pathway from mothers to infants may be mediated by certain parenting behaviors, such as maternal co-sleeping at bedtime.     

The reliability of nocturnal vaginal blood flow

Fourteen subjects participated in a sleep study designed to document the reliability of measurements of REM-related vaginal blood-flow changes. Several standard sleep parameters were also examined for comparison with vaginal measures. The most reliable vaginal measure was the maximal change in disengorgement for a given REM period averaged across a night of REM periods. The reliability of this measure compared favorably with that of a highly reliable computerized measure of REM density. It is suggested that nocturnal vaginal blood-flow measures have sufficient reliability to be useful in the differential diagnosis of organic and psychogenic sexual dysfunction.This study was supported in part by a training grant to the Department of Clinical Psychology, University of Florida, Gainesville (USPHS532DE07133-02), and a grant from the NIH (USPHSCA26364R073241-29) to the second author.     

BEHAVIOR MANAGEMENT OF INFANT SLEEP DISTURBANCE

Using a nonconcurrent multiple baseline design, we evaluated the effects of extinction and stimulus control on nighttime sleep disturbances exhibited by 7 infants. Results showed that frequency and duration of night wakings decreased for all subjects, with corresponding improvements reflected through changes in responses to the sleep behavior scale. Observed improvements maintained at 3 and 24 months posttreatment.