Ethnicity, sleep duration, and sleep satisfaction

Analysis of responses of 1100 students from four ethnic groups to questions about the quantity and quality of their sleep indicated that ethnicity was modestly but significantly related.     

Information processing during sleep onset and sleep.

This Special Section examines the extent of information processing during sleep onset and sleep itself. It is generally agreed that, stimulus input is markedly inhibited during sleep, thus preventing conscious awareness of the external environment. Overt behavioural responses are rarely made within sleep. Two neurophysiological measures are therefore often used. The electrical activity of the brain (the EEG) can be employed to distinguish waking (conscious) from sleeping (unconscious) states. It is also possible to quantify the EEG prior to and following a detection (or a failure of a detection) of a stimulus. Such measures can thus be used to predict conscious awareness. A second measure that frequently has been employed is the brain's response to an external stimulus (the evoked potential). Different components of the evoked potential can be used to trace the extent of information processing during the different states of consciousness. Some are associated with a preconscious detection while others are associated with conscious awareness. Other evoked potentials may be unique to sleep.     

Worry and sleep length revisited: worry,sleep length,and sleep disturbance ascribed to worry

The author administered university students (N = 222; 152 women, 70 men) the Worry Domains Questionnaire (F. Tallis, G. C. L. Davey, & A. Bond, 1994) and a newly constructed scale (the Sleep Disturbance Ascribed to Worry Scale) to measure sleep disturbance attributed to worry. To revisit previous studies (i.e., E. Hartmann, F. Baekeland, & G. R. Zwilling, 1972; S. J. H. McCann & L. L. Stewin, 1988) that suggested that sleep length was positively related to worry, the author also asked the students a question about habitual sleep length. The results indicated that worry and sleep disturbance attributed to worry were negatively related to sleep length. A regression analysis revealed that worry was significantly negatively related to habitual sleep length irrespective of sleep disturbance ascribed to worry.     

Spiral aftereffect durations following awakening from REM sleep and non-REM sleep

Nine Ss were awakened 2 min after the beginning of a REM period and 2 min after the beginning of a non-REM period (Stage 4), and were tested on a spiral aftereffect. The duration of the spiral aftereffect was found to be longer for the tests made following REM periods than for the tests made following non-REM periods. The results were interpreted to suggest a possible “carry over” effect from the particular sleep, stage into the waking state.     

Behavioral,subjective, and electroencephalographic indices of sleep onset latency and sleep duration

Electrographic (EEG, EOG, EMG) indices have been used for some decades in the definition of the stages of sleep and more recently in the diagnosis of sleep-related disorders, e.g., insomnia, despite the lack of detailed information concerning the precise relationship between such electrographic indices and behavioral and subjective criteria of sleep. Evaluation of the relationship between EEG, behavioral, and self-report measures of sleep onset latency and sleep duration was conducted using 17 young normal sleepers. The behavioral measure was provided by an apparatus which records subjects' button-press responses to an auditory stimulus presented at various interstimulus intervals (2, 5, and random 1, 2, 5, 7, and 10 min). The behavioral and stage 2 EEG estimates of sleep onset latency (SOL) and sleep duration (SD) were almost identical. The stage 1 EEG provided the shortest estimate of SOL; the self-report measure, the longest. The SD measures were in reverse order. There were no significant differences among the three interstimulus interval conditions (2, 5, and random min). Average response rates to the 50-dB chime were 100% during wakefulness, 81% during EEG stage 1, and 8% during EEG stage 2. Almost all stage 2 responding occurred during the first 5 min of each stage 2 period. The validity of electrographic indices as sleep criteria and the implications of the findings for the formulation of an adequate definition of sleep and its clinical measurement are discussed.     

Noise and loss of sleep

Two experiments are reported in which human performance was compared under continuous 90 dB. white noise, after loss of sleep, under a combination of the two and under appropriate control conditions. The results suggest that noise is effective in reducing the deterioration in performance, characteristic of loss of sleep. The relevance of the result to the arousal theory of loss of sleep is discussed.     

Object concept and sleep regulation

The association between infants' cognitive development and sleep regulation was investigated in 83 infants not at risk. It was found that 9-mo.-old infants with a more advanced object concept had significantly fewer sleep difficulties compared to infants with lower level of object permanence.     

Obstructive sleep apnea and depression

Is there an association between obstructive sleep apnea (OSA) and depression? OSA is a common breathing-related sleep disorder. There have been reports that depressive symptoms can be associated with this sleep disorder. A number of investigations have addressed this issue. Although some have found no correlation, most studies have concluded that there is an association between OSA and depressive symptoms. Other investigations have shown that depressive symptoms improve with treatment of OSA, and that untreated OSA may contribute to treatment resistance in some cases of mood disorders. Within the framework of current psychiatric diagnostic criteria, the depressive symptoms associated with OSA can be viewed as a combination of a mood disorder secondary to a primary medical condition and an adjustment disorder with depressed mood. The question of whether OSA causes depressive symptoms can perhaps be best answered by viewing OSA and depression as having certain symptoms that are common to both disorders.     

Time perspective and sleep problems

In this study of 137 university students, we examined the relationships among the five dimensions of the Zimbardo Time Perspective Inventory and three scales that measure aspects of sleep problems. All of the Zimbardo Inventory dimensions correlated significantly with each of the sleep problem-related scales. These data suggest that concern about time, regardless of the specific nature of individuals' time perspective, and certain sleep problems are significantly related.     

Reported sleep: needed minus obtained sleep, family resemblance, and age

For a normal population from 13 to 89 yr. of age there was a correlation of .02 between age and sleep obtained, -.07 between age and sleep needed, and -.33 (p less than .01) between age and sleep needed minus sleep obtained. Also, significant family resemblance was found for all three of the above sleep variables.     

The effect of a delayed weekend sleep pattern on sleep and morning functioning

Abstract

It is a common practice for young adults to delay their weekend sleep schedule. The present study was designed to assess the effect of this sleep pattern on the sleep of Sunday night and the functioning of Monday morning. The sleep schedules of 30 young adults were manipulated for 2 consecutive weeks. In the Habitual-Sleep (HS) week, subjects followed their habitual sleep schedule throughout the week; in the Delayed-Sleep (DS) week, subjects' sleep schedule on Friday and Saturday nights were delayed by two hours. Compared to the HS week, subjects showed significantly lower subjective sleepiness near bedtime and trends of longer sleep onset latency on Sunday night in the DS week. In addition, there was both lowered cognitive performance and overall mood rating on Monday morning in the DS week. The delayed weekend sleep pattern contributes to Sunday night insomnia and the Monday morning “blues”.     

Rapid eye movement sleep deprivation affects sleep similarly in castrated and noncastrated rats

Twenty-four-hour recordings of electrophysiological correlates of the sleep-waking cycle in castrated and noncastrated Wistar rats were performed to validate the cuff pedestal technique in the deprivation of rapid eye movement sleep. An undisturbed pattern of sleep was found in both castrated and noncastrated rats when the cuffs were in the raised position. The lowering of the cuff for 4 days virtually abolished REMs in both groups of rats. During neither the dark nor the light period was there any difference between the castrated and noncastrated rats in the total amount of REMs rebound. The results accord with the data obtained by the conventional flowerpot procedure and show that castration does not influence the amount of REMs before, during, and after REMs deprivation in the rat. It is suggested that testicular testosterone, contrary to growth hormone, is not essential for the triggering of REMs sleep, although both have anabolic actions.