A behavioural basis for distinguishing wakefulness from sleep in insomniac and good sleepers.

Distinguished between the sleep of normal Ss and insomniacs, using the behaviorally-based sleep/wake monitor. 18 Ss with insomnia (aged 26–65 yrs) and 11 controls (aged 30–44 yrs) underwent a hearing test, and completed the Brock Sleep and Insomnia Questionnaire (K. A. Cote and R. D. Ogilvie, 1993). They used the behavioral response sleep/wake monitors for 3 consecutive nights, to assess behavioral sleep data. Results indicate group differences for wakefulness, sleep onset latency, total percent sleep, and percent wakefulness prior to sleep onset. Significant night effects were present in a number of measures. Group by Night interactions were found for total percent sleep, and after sleep onset, total percent wakefulness and after sleep onset. These findings support differences between normal and insomniac sleep. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of mood on sleep onset latency and REM sleep in interepisode bipolar disorder.

The present study investigates whether interepisode mood regulation impairment contributes to disturbances in sleep onset latency (SOL) and rapid eye movement (REM) sleep. Individuals with interepisode bipolar disorder (n = 28) and healthy controls (n = 28) slept in the laboratory for 2 baseline nights, a happy mood induction night, and a sad mood induction night. There was a significant interaction whereby on the happy mood induction night the bipolar group exhibited significantly longer SOL than did the control group, while there was no difference on the baseline nights. In addition, control participants exhibited shorter SOL on the happy mood induction night compared to the baseline nights, a finding that was not observed in the bipolar group. On the sad mood induction night, participants in both groups had shorter SOL and increased REM density when compared to the baseline nights. Bipolar participants exhibited heightened REM density compared to control participants on both nights. These results raise the possibility that regulation of positive stimuli may be a contributor to difficulties with SOL, while hyperactivity may be characteristic of REM sleep. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electrophysiological changes during the sleep onset period of psychophysiological insomniacs, psychiatric insomniacs, and normal sleepers

The electroencephalograms (EEGs) of the sleep onset period (SOP) of psychophysiogical insomniacs. psychiatric insomniacs, and controls were compared using power spectral analysis. We predicted that psychophysiological insomniacs would show elevated cortical arousal throughout their entry into sleep. Electroencephalograms, electrooculograms (EOGs), and electromyograms (EMGs) were recorded for two consecutive nights. Power spectral analysis of EEG from the sleep onset period was performed on all standard frequency bands. Psychophysiological insomniacs had less alpha during the first part of the SOP and did not show the dramatic drop in alpha across the SOP that characterizes normal sleep. They showed less delta in the last quartile of the chronological analysis of the SOP. Psychiatric insomniacs showed lower relative beta power values overall, while psychophysiological insomniacs showed higher relative beta power values during wakefulness. This microanalysis indicates that the SOP is generally similar for psychiatric insomniacs and normal sleepers but that clear differences in the SOP of psychophysiological insomniacs exist. They have higher cortical arousal during the SOP than do psychiatric insomniacs and controls. The dramatic changes in power values in the latter two groups as sleep begins are not seen in the psychophysiological insomniacs, which may help explain the difficulty that psychophysiological insomniacs have discriminating between wakefulness and sleep.     

Effect of mobile phase composition on the binding kinetics of chiral solutes on a protein-based high-performance liquid chromatography column: interactions of D- and L-tryptophan with immobilized human serum albumin

The relationship between central nervous system serotonergic activity, as reflected by cerebrospinal fluid (CSF) concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), and sleep/wakefulness behavior was investigated in socially housed, juvenile rhesus macaques. Two cohorts of rhesus monkeys (Macaca mulatta), numbering 42 subjects (seventeen 39-month-olds and twenty-five 20-month-olds) were observed in their home cages between 21.30 h and 23.30 h for 10 nights using an infrared night scope. Over each 90-min observation period, the following states were recorded every 5 min using a scan sampling procedure: Sleep, Drowsy, Passive-awake and Active. After more than one quarter of the animals in the group had fallen asleep, states were recorded as they occurred. Six weeks prior to the collection of the behavioral data, a sample of cisternal CSF was obtained to assay for 5-HIAA concentrations. With cohort effects statistically controlled, there was a negative correlation between latency to fall asleep and CSF 5-HIAA concentrations (i.e., subjects with high CSF 5-HIAA concentrations were more likely to fall asleep early). Subjects with low CSF 5-HIAA concentrations were also more active during the daytime hours. Subjects who fell asleep first were, on average, also less active during nighttime hours. The positive correlation between CSF 5-HIAA and sleep onset was not a result of social status since there was no correlation between social dominance rank and time of sleep onset. These results support the hypothesis that the serotonergic system may play a role in sleep onset and possibly in the regulation of diurnal activity rhythms in non-human primates.     

Phenomenology of sleep among insomniacs and good sleepers: Wakefulness experience when cortically asleep.

25 insomniacs and 10 good sleepers (undergraduates) slept in a laboratory for 2 consecutive nights and for an intervening daytime nap session. Ss were awakened at the end of the 10th consecutive epoch of initial Stage 2 sleep and were asked to report on their experiences of sleep or wakefulness. EEG data were also collected. Insomniacs reported less sleep experience than did good sleepers in both the night and nap sessions. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of densensitization on the sleep and dreams of a phobic subject.

Studied the sleep and dreams of a 22-yr-old male undergraduate who had complained of fear of noise and closed spaces and had consequently undergone 9 1-hr desensitization sessions within a 2-wk period. On 11 nights, prior to, during, and after sensitization training, the S slept in an air-conditioned, sound-proof experimental room while his physiological responses were monitored. The 1st 2 nights were adaptation nights, the 3rd night was a dream collection night, and the remaining 8 nights consisted of 2 blocks of nonconsecutive nights which were used to record uninterrupted sleep or to collect dreams. Upon being awakened on dream nights, the S reported dream content and rated each dream on a modified version of the Nowlis Mood Adjective Checklist (NMAC). Data show that time to get to sleep (associated with anxiety), REM density (associated with bizarreness and emotionality), and 2 inner-focused negative affect dimensions of the NMAC exhibited a 'U'-shaped function over the course of the study. Findings indicate that removal of affective discharge from what were usually disturbing stimuli reduced the effects of such stimuli on sleep and dreams. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes in EEG power density during sleep laboratory adaptation

First- and second-night effects on the electroencephalogram (EEG) were investigated by means of polygraphic sleep recordings and all-night spectral analysis. Eighteen normal subjects were studied for three consecutive nights in a hospital sleep laboratory. Visual sleep scoring showed that there was a first-night effect in normal subjects similar to that reported previously [increased wakefulness; decreased total sleep time, sleep efficiency, and rapid eye movement (REM) sleep]. Spectral analysis of the sleep EEG revealed important changes, most of which occurred in REM sleep. Increased delta, theta, and beta1 power densities accompanied by decreased mean frequency were seen in REM sleep in the second night. On the basis of REM sleep deprivation results previously published, our data suggest that the second night could be affected by partial REM sleep deprivation that occurred in the first night. Delta and theta power density values decreased in the first non-rapid eye movement episode of nights 1 and 2; this could result from increased REM sleep pressure. The overall consistency of spectral data in the first and second night with REM sleep findings derived from visual scoring in the first night lends further support to this hypothesis. The sleep disturbance experienced during the first night in a sleep laboratory may be a useful and valid model of transient insomnia. Therefore, we conclude that data from all nights recorded should be included in assessing a subject's sleep.     

Model of a miniature pig catheterized for pharmacokinetic and pharmacodynamic studies of anti-infective agents

The purpose of this study was to examine the role of sleep problems in the etiology of nursing caries. Two-hundred mothers of children (104 with nursing caries and 96 caries free) from ages 2 to 4.5 years were surveyed to determine whether difficulty with child sleep and ensuing sleep-associated feeding might be related to the presence of nursing caries. Differences were noted between these two groups regarding: average number of nights the child slept through the night (P < 0.001); total hours of sleep per night (P < 0.05); frequency of night waking episodes (P < 0.01); feeding on demand upon waking (P < 0.01); using a bottle to assist with falling asleep at night (P < 0.001); and feeding in association with nap time (P < 0.001). Differences also were noted in regard to average age of weaning (P < 0.001). Our findings suggest that sleep problems among young children are a behavioral risk factor for night-time bottle use and early childhood caries.     

Effects of sleeping in a chemical protective mask on sleep quality and cognitive performance

PURPOSE: We wanted to determine whether sleep is disrupted when soldiers sleep in a new chemical protective mask, the M40. Sleep quantity and quality, extent of protection provided by the mask during sleep, and next day performance were assessed. METHOD: After several days of training, 9 male soldiers slept with and without the M40 mask on four occasions. RESULTS: Soldiers were able to tolerate the mask for most or all of the night. However, sleep, as assessed by wrist-worn activity monitors, was significantly disturbed. Minutes (mean +/- SEM) of waking significantly increased, from 25 +/- 2.1 to 86 +/- 8.5 per night (p < 0.001), and number of awakenings rose from 8 +/- 0.6 to 20 +/- 0.9 (p < 0.0001). Soldiers reported that it took longer and was more difficult to fall asleep when wearing the mask. Errors on a choice reaction time task increased significantly and subjects reported greater fatigue and sleepiness the day after sleeping in the mask. Protection provided by the masks varied substantially among subjects and declined over the course of the study. Some soldiers were protected throughout the night but others were only protected intermittently. CONCLUSION: We conclude that sleeping in the chemical protective mask should only be done when necessary, given the adverse effects on sleep and daytime function, as well as the variability of protection, of the mask.     

Mesograde amnesia during the sleep onset transition: replication and electrophysiological correlates

The present study was designed to explore mechanisms of amnesia for meaningful auditory material presented during the sleep onset transition. Thirty undergraduate subjects (17 female, 13 male) were presented with auditory stimuli in an oddball paradigm until sleep onset. Subjects were allowed to accumulate either 30 seconds or 10 minutes of sleep, then awakened and tested on free recall and recognition memory for the meaningful stimuli. After 10 minutes of sleep, but not after 30 seconds of sleep, subjects had profound amnesia on free recall for stimuli presented in the 4-minute window prior to sleep onset. Increased beta electroencephalograph (EEG) power during the sleep period correlated positively with recall of stimuli in the 4-minute presleep window. Event-related potential recordings provided suggestive evidence that subjects continued to process the auditory stimuli to some extent during the sleep onset transition. When allowed to sleep for 10 minutes, subjects evidenced a mixed anterograde and retrograde amnesia for auditory stimuli presented in the 4-minute window prior to sleep onset. The results are discussed in terms of stimulus encoding, consolidation, and retrieval.     

Mood and sleep in aging women.

Examined the possible covariations of mood and sleep in a 5-yr follow-up of 25 normal, aging women (aged 56–66 yrs) who had originally participated in the 2nd author's (1982) study. Ss slept in the laboratory for 4 nights. Wiring for EEG recording began at 10:00 PM and a mood inventory was administered at 10:30 PM on the last 3 nights. Ss went to sleep at 11:00 PM, and EEG recording was continuous from bedtime until wake-up the following morning. Results show that mood assessments were independently related to both before and after sleep night. Only 2 sleep variables, sleep efficiency and latency to 1st REM period, were reliably related to daytime moods. The relative paucity of relation between mood and sleep variables was interpreted as reflecting a general insulation of sleep from day-to-day mood variations. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polysomnographic sleep is not clinically impaired in Vietnam combat veterans with chronic posttraumatic stress disorder

BACKGROUND: Because sleep is typically disturbed in posttraumatic stress disorder (PTSD), this study was undertaken to evaluate a group of Vietnam combat veterans with the disorder using clinical polysomnographic techniques. METHODS: Eighteen Vietnam combat veterans with PTSD and 10 healthy non-combat-exposed Vietnam era veterans participated in 2 nights of polysomnographic study and a multiple sleep latency test. RESULTS: No significant differences between subjects and controls were noted except for greater sleep onset latency to stage 2 (p < .03), and lower arousals/hour from stages 3 & 4 (p < .04) on night 2, and lower subjectively estimated total sleep time on night 1 (p < .005) in the case of PTSD subjects. Otherwise, results from the second night served to replicate those from the first, and no significant differences appeared on 2 successive nights for any polysomnographic variable. No daytime hypersomnolence was detected. CONCLUSIONS: Polysomnographically recorded sleep was notably better than expected in the presence of clinically significant PTSD with typical histories of disrupted sleep. In these subjects, there is no clinically significant sleep disorder or typical pattern of sleep disturbance detectable by standard polysomnography.     

Absence of tonic electromyographic activity during sleep in normal and spastic nonmimetic skeletal muscles in man

An electromyographic study of nonmimetic skeletal muscles was carried out in 8 normal adults and 4 patients with spastic hemiparesis during all stages of sleep for a total of 21 nights. All normal subjects showed absence of tonic electromyographic activity in all nonmimetic skeletal muscles in all stages of sleep. Also, during quiet, relaxed wakefulness, tonic muscle discharges disappeared in the normal subjects. Three patients with upper motor neuron spasticity demonstrated results during sleep similar to those obtained in the normal subjects. In the fourth patient, tonic muscle discharges persisted into stage 2 non-REM sleep, disappeared within 30 to 240 seconds following the onset of stage 2 sleep, and were absent during stages 3 and 4 sleep and REM sleep.     

Activation of a distinct arousal state immediately after spontaneous awakening from sleep

In contrast to the many neural studies into the mechanisms of sleep onset and maintenance, few studies have focused specifically on awakening from sleep. However, the abrupt electrographic changes and large brief cardio-respiratory activation at awakening suggest that a distinct, transiently aroused, awake state may exist compared to later wakefulness. To test this hypothesis we utilized the acoustic startle reflex, a standard un-conditioned reflex elicited by a sudden loud noise. This reflex is modulated under specific conditions, one being a diminution of startle when a quieter pre-stimulus is presented immediately before the loud stimulus. This pre-pulse inhibition (PPI) is used as a measure of sensorimotor gating, with smaller PPI indicating less filtering of sensory inputs and increased responsiveness to external stimuli. Eight rats with electrodes for recording sleep-wake state were studied. An accelerometer measured startle responses. The startle reflex was elicited by 115 dB, 40 ms tones. PPI was produced by 74 dB, 20 ms tones preceding the 115 dB tone by 100 ms. Responses within 100 ms were measured. Stimuli were applied either 3-10 s after spontaneous awakenings, or in established wakefulness (> 30 s). Responses to the startle stimuli alone were similar in the different awake states (P = 0.821). However, PPI was smaller at awakening from non-REM sleep compared to established wakefulness (45.4 +/- 7.5% vs. 74.3 +/- 6.1%, P = 0.0002). PPI after awakening from REM sleep (52.8 +/- 17.9%) was not significantly different than established wakefulness (P = 0.297). Reduced PPI of the startle reflex at awakening from non-REM sleep supports the hypothesis that wakefulness immediately after spontaneous sleep episodes is neurophysiologically distinct from later wakefulness and associated with reduced gating of motor responses to sensory inputs. Spontaneous activation of this distinct, transiently aroused, state upon awakening may serve a protective function, preparing an animal to respond immediately to potentially threatening stimuli.     

Effects of two kinds of pillow on thermoregulatory responses during night sleep

We compared thermoregulatory responses during night sleep between two kinds of pillow. One has special cool medium consisting of sodium sulfate and ceramic fiber (pillow A) and the other polyester padding (pillow B). The subjects wore 100% cotton thin pajamas with short sleeves and three-quarters trousers for summer use. They lay and slept in bed with cotton sleeping mat and cotton quilt between 10:30 p.m. and 6:30 a.m. in a bed room with an ambient temperature (Ta) of 27 +/- 1 degrees C and a relative humidity of 55 +/- 5%, using either of the pillow A or pillow B. When they awoke, the subjects filled out a questionnaire on how well they slept during sleep. Main results were: 1) Rectal and forehead skin temperatures and heart rate were kept significantly lower in the pillow A during the latter half of the night sleep. 2) Palm and thigh skin temperatures were significantly higher mostly in the pillow A. 3) All the subjects regarded the pillow A better for deeper sleep. It was concluded that slight cooling of the head due to the pillow A during night sleep seemed to be of significance for deep sleep.     

The impact of prestimulus EEG frequency on auditory evoked potentials during sleep onset.

Assessed stimulus relevance vs rarity effects by investigating the N550 to stimuli identified as targets during wakefulness compared to the N550 in response to deviant stimuli with the same probability of occurrence without the target identification. Five Ss (mean age of 22.3 yrs) had their auditory evoked potentials recorded during wakefulness, Stage 1, and Stage 2 non-REM sleep using a 3-tone auditory oddball paradigm. Stage 1 sleep was divided into trials preceded by alpha and those preceded by theta. Results indicate that a negative wave peaking at about 100 ms, N1, displayed a significant decrease in amplitude with the onset of Stage 2 sleep. A later N2 peaked at about 250 ms in the waking state. This changed into a sleep-specific negative wave peaking at 300 ms (N300) at the alpha-theta transition within Stage 1. The P300 displayed a similar shift to become a P450 in Stage 2 sleep. N550 was specific to Stage 2, and was larger in response to rare, rather than frequent stimuli. There was no evidence of any enhancement to relevant rare stimuli compared with irrelevant rare stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Objective sleep measures and subjective sleep satisfaction: How do older adults with insomnia define a good night's sleep?

The relationship between objective sleep measures and subjective sleep satisfaction was explored in a sample of 47 older adults (59 years and older; 35 women, 12 men) with primary insomnia. Participants submitted to all-night sleep evaluations (polysomnography) for 2 nights. After each night, participants provided subjective sleep-satisfaction ratings. Depth of sleep (decreased Stage 1 sleep and increased Stages 3 and 4 sleep) and sleep latency were the best predictors of subjective sleep satisfaction. For other sleep variables such as sleep efficiency and wake time after sleep onset, no value predicted satisfaction on a particular night. However, for these sleep variables, relative improvement from Night 1 to Night 2 predicted greater subjective satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Brain networks affected by synchronized sleep visualized by positron emission tomography

Nineteen lightly sleep-deprived healthy volunteers were examined with H2(15)O and positron emission tomography (PET). Scanning was performed during wakefulness and after the subjects had fallen asleep. Sleep stage was graded retrospectively from electroencephalogram (EEG) recordings, and scans were divided into two groups: wakefulness or synchronized sleep. Global flow was quantified, revealing no difference between sleep and wakefulness. A pixel-by-pixel-blocked one-way analysis of variance (ANOVA) was performed after correcting for differences in anatomy and global flow. The sum of squares of the z-score distribution showed a highly significant (P < 0.00001) omnibus difference between sleep and wakefulness. The z-score images indicated decreased flow in the thalamus and the frontal and parietal association cortices and increased flow in the cerebellum during sleep. A principal component (PC) analysis was performed on data after correction for global flow and block effects, and a multivariate analysis of variance (MANOVA) on all PC scores revealed significant (P = 0.00004) differences between sleep and wakefulness. Principal component's 2 and 5 correlated to sleep and revealed distinct networks consisting of PC 2, cerebellum and frontal and parietal association cortices, and PC 5, thalamus.     

Use of paradoxical intention in a behavioral program for sleep onset insomnia.

Sleep onset insomnia seems often to be based on performance anxiety associated with a client's fears of being able to fall asleep; in some cases, a therapeutic program might actually exacerbate this performance anxiety by focusing on the client's efforts to voluntarily control the sleep onset process. Five Ss aged 23–41 yrs and experiencing sleep onset difficulty unusually resistant to a conventional behavioral program for this problem (i.e., deep muscle relaxation and systematic desensitization), were exposed to paradoxical intention suggestions requiring that they try to remain awake as long as possible, rather than attempt to fall asleep. A rapid reduction of sleep onset latency occurred following the shift from the conventional program to the paradoxical intention instructions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fatigue and sleep in chronic headache sufferers: an age- and sex-controlled questionnaire study

We studied fatigue and sleep in chronic headache sufferers in comparison to age- and sex-matched controls. We determined the prevalence and intensity of fatigue as well as several sleep features. The study was conducted in a headache center through the use of a questionnaire. One hundred thirteen headache sufferers (59 men and 54 women) and 110 controls (56 men and 54 women) were included in the analysis. Fatigue was found to be equally common in the headache sufferers (70.3%) and in the controls (60.0%). However, the headache sufferers rated the intensity of their fatigue significantly higher (4.1 versus 2.8 cm on a 10-cm visual analog scale). When the sexes were considered separately, the difference in intensity of the fatigue between the two groups was significant only for the women (5.1 versus 3.0 cm). With regard to sleep, the headache sufferers slept significantly shorter (6.7 hours) than the controls (7.0 hours). It also took them longer to fall asleep (31.4 versus 21.1 minutes) and longer to fall back asleep after waking up at night (28.5 versus 14.6 minutes). When the sexes were considered separately, the differences in sleep features between the two groups were significant only for the men. On the basis of these results, we conclude that chronic headache sufferers feel more tired, especially the women, and do not sleep as well at night, especially the men. Further study is necessary to determine the significance of these findings in relation to chronic headache suffering.