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Biomedical subjects

T H Monk

Publications and source records attributed to T H Monk.

At least 55 records · Page 3Linked to original sources
PubMed1996

Amplitude reduction of the circadian temperature and sleep rhythms in the elderly.

This study examined the relationship between circadian temperature rhythm amplitude reduction and sleep consolidation parameters in a group of healthy elders experiencing a 6-h phase advance in routine. Twenty-five healthy old people (15 women, 10 men, 77-91 years old) lived in a time-isolation apartment. Throughout the study, subjects were instructed when to go to bed, get up, and take meals. The experiment started with 5 baseline days during which subjects were kept to a daily routine corresponding to their habitual sleep-wake cycle. The wake time of the 6th night was phase-advanced by 6 h and the routine for the remainder of the experiment was held constant at the new earlier phase position. Rectal temperature was recorded continuously and all sleep episodes recorded polygraphically. Time series of temperature data for each subject were analyzed by complex demodulation (CD). Five of the subjects were excluded from analysis because the percentage of variance accounted for by the remodulate was less than 55% for the postshift days and one subject was excluded because he showed an average sleep efficiency of less than 55% during baseline. In the remaining 19 subjects, the phase shift produced a large decrease of the mean amplitude of the temperature circadian rhythm (from 0.45 degree C to 0.25 degree C). During the first 3 nights following the phase shift, sleep efficiency was decreased and amount of wakefulness in the first half of the night (WFirst) was increased. No effect was found for the amount of wake in the second half of the night (WSecond). The change in amplitude of the temperature rhythm was significantly correlated with change in sleep efficiency (r = 0.5; p = 0.03) and with change in WFirst (r = -0.7; p < 0.001). There was no correlation between change in the amplitude of the temperature rhythm and WSecond. These results suggest that in older subjects, amplitude of the output of the circadian oscillator might indeed be involved in the sleep consolidation process but, in the first, rather than the second half of the night.

Aged↗
PubMed1996

Circadian determinants of the postlunch dip in performance.

This study compared rectal temperature rhythms in groups of subjects who either did (n = 5) or did not (n = 7) show a clear postlunch dip in performance at a monotonous (25-30 min) vigilance task. Performance was tested every 2h in a standardized routine with lunch replaced by hourly liquid food supplements. Those showing the postlunch performance dip had a higher amplitude and later peaking 12h component to their rectal temperature rhythm that those who did not, resulting in flat, rather than rising, temperatures over the 10:00-15:00 time interval. The effect could not be explained by intergroup differences in prior sleep, morningness, or gender, although there was a trend (p = 0.09) for the "dip" group to be slightly younger (21.8y vs. 24.2y). The postlunch dip appears to be an endogenous phenomenon individually determined, but related to the strength of the (12h) harmonic of the circadian system.

Adult↗
PubMed1995

Delayed sleep phase syndrome: a review of its clinical aspects.

OBJECTIVE: Delayed sleep phase syndrome is a common but little reported cause of severe insomnia. Since it was first described, few detailed reports of delayed sleep phase syndrome have appeared, and treatment methods have not been reviewed. From the literature, the authors provide diagnostic descriptions and review treatment methods, and from their sleep disorder clinic, they describe the management and outcome of the largest series of patients with delayed sleep phase syndrome thus far reported. METHOD: The authors reviewed all articles with primary data on delayed sleep phase syndrome published through 1993 and add data from a group of 33 patients at their sleep disorder clinic. RESULTS: Delayed sleep phase syndrome involves undesirably late bedtimes and arising times, early night insomnia, and poor morning alertness but lack of insomnia on vacations. The mean bedtime and arising time for the 33 patients were 4:00 a.m. and 10:38 a.m., respectively. Twenty-five patients were, or had been, depressed. Individual responses to treatments varied widely. Seventeen patients showed little treatment response. Delayed sleep phase syndrome had a worse treatment outcome than other sleep disorders. CONCLUSIONS: Delayed sleep phase syndrome presents in a heterogeneous manner. In the sleep disorder clinic population, it was often associated with major depression and was more resistant to treatment than other sleep disorders. Multiple and varied treatments are required.

Adolescent↗
PubMed1994

Social rhythm in anxiety disorder patients.

UNLABELLED: The social rhythm metric (SRM) is a self report diary instrument which generates a numerical measure of rhythmicity of daily life behaviors. Depression researchers have proposed that life events cause disruption of social rhythmicity and this leads to disturbance in the sense of well-being and to disruption of physiologic rhythmicity known to be related to depressive episodes. We hypothesized that low rhythmicity of daily activities might also be characteristic of anxiety disorder patients. SUBJECTS: Forty-eight patients who met DSM III-R criteria for an anxiety disorder were recruited and compared with 41 previously monitored normal controls. PROCEDURES: All patients and controls completed at least two weeks of daily monitoring with the SRM. Anxiety patients underwent structured diagnostic assessment and completed demographic and clinical rating scales. SRM was analyzed according to a previously developed algorithm. RESULTS: Anxiety disorder patients report significantly lower regularity of daily activities than normal controls. The low SRM scores were not accounted for by the presence of comorbid affective disorder. CONCLUSIONS: We identify a new type of abnormality in anxiety disorder patients which has potential clinical as well as theoretical interest.

Activities of Daily Living↗
PubMed1994

Nocturnal and circadian body temperatures of depressed outpatients during symptomatic and recovered states.

Forty-one recurrent unipolar depressed outpatients were studied at baseline (symptomatic period) and at recovery. Rectal temperatures were measured continuously between 1800h and 0600h on 2 successive nights at each time point. In those 24 patients who recovered after receiving interpersonal psychotherapy (IPT) alone ("psychotherapy responders") and who thus remained drug-free throughout, there was no difference in nocturnal body temperatures between baseline and recovery time points. Moreover, nocturnal temperature patterns appeared to be very similar to those of a healthy contrast group (n = 17). The contrast group was not matched for age and gender with the patient group, though, so the comparison was only suggestive. At baseline, those recovering after psychotherapy alone (n = 24) did not differ from those eventually failing to respond to IPT and requiring medications to achieve recovery ("medication responders") (n = 17). Medication responders did show some baseline versus recovery differences in nocturnal temperatures, but these may possibly have been a function of the medications used. At recovery, a subset of 19 psychotherapy responders and 13 medication responders underwent an "unmasking" experiment involving 36 hours of wakeful bedrest. In the resulting endogenous temperature rhythms, there was no evidence of any reliable differences between the psychotherapy responder and medication responder patient groups. Both groups showed rhythms that were very similar to those of a healthy contrast group (n = 17), although, again, the contrast group was not matched for age or gender with the patient group. In conclusion, in measures of body temperature, at least, there appeared to be little evidence of circadian dysfunction in this group of recurrent outpatient depressives.

Adult↗
PubMed1994

Psychosocial correlates and sequelae of electroencephalographic sleep in healthy elders.

This research examines longitudinal data on psychosocial status and polysomnographic sleep collected annually from 57 healthy, community-residing elders aged 61-89. Cluster analysis of variables reflecting sleep continuity and architecture at the baseline assessment was used to identify three groups of elders: those whose sleep was either (a) superior to all remaining respondents across a variety of measures, (b) marred only by significantly reduced sleep efficiency relative to other respondents, or (c) poorer than all other respondents in multiple areas. Cross-validation procedures suggested that the three-group cluster solution was stable and replicable over persons and over time. Subsequent multivariate analyses indicated that recent life events, as well as psychosocial stability and support variables at baseline, distinguished between the sleep pattern groups. Moreover, sleep pattern group membership itself predicted subjects' subsequent sleep characteristics and psychosocial status at follow-up. Implications of these results for conceptualizing psychosocial factors that affect, and are ultimately affected by, sleep disturbances in late life are discussed.

Aged↗
PubMed1994

A longitudinal study of laboratory- and diary-based sleep measures in healthy "old old" and "young old" volunteers.

The major aim of this study was to examine laboratory- and diary-based measures of sleep in a group of healthy ("successfully aging") "old old" subjects (> or = 75 years of age), as contrasted with a group of "young old" subjects (60-74 years of age), who were followed longitudinally for 2 years. We hypothesized that sleep would deteriorate to a greater extent over time among the old old subjects than among the young old. The study group consisted of 50 elders (21 male, 29 female; 23 old old, 27 young old), each studied at baseline and then again at 1- and 2-year follow-up. Analysis of variance was used to determine main effects of age group, gender and time on key sleep measures. Most measures were found to be remarkably stable over time. However, some decay was detected in sleep efficiency among the old old, but not among the young old. In a multiple regression model for the cohort as a whole, age, cognitive status and medical burden at baseline predicted subsequent declines in sleep efficiency over the 2-year period. To our knowledge, this is the first longitudinal data set on sleep in the healthy old old.

Aged↗
PubMed1994

Supporting shift workers.

In interviews with nurses across the United States, the authors became aware of the significant effect nurse executives, nurse managers, staff educators, and researchers had on the lives of nurse shift workers, and on their adjustment to permanent and rotating shift work. In this excerpt from their book, The Nurse's Shift Work Handbook, the authors discuss the importance of the shift system, shift worker selection factors, and the ways nurse administrators can foster shift workers' adaptation through education and supportive services.

Circadian Rhythm↗
PubMed1994

Regularity of daily life in relation to personality, age, gender, sleep quality and circadian rhythms.

A diary-like instrument to measure lifestyle regularity (the 'Social Rhythm Metric'-SRM) was given to 96 subjects (48 women, 48 men), 39 of whom repeated the study after at least one year, with additional objective measures of rest/activity. Lifestyle regularity as measured by the SRM related to age, morningness, subjective sleep quality and time-of-day variations in alertness, but not to gender, extroversion or neuroticism. Statistically significant test-retest correlations of about 0.4 emerged for SRM scores over the 12-30 month delay. Diary-based estimates of bedtime and waketime appeared fairly reliable. In a further study of healthy young men, 4 high SRM scorers ('regular') had a deeper nocturnal body temperature trough than 5 low SRM scorers ('irregular'), suggesting a better functioning circadian system in the 'regular' group.

Adult↗
PubMed1994

The Pittsburgh Sleep Diary.

Increasingly, there is a need in both research and clinical practice to document and quantify sleep and waking behaviors in a comprehensive manner. The Pittsburgh Sleep Diary (PghSD) is an instrument with separate components to be completed at bedtime and waketime. Bedtime components relate to the events of the day preceding the sleep, waketime components to the sleep period just completed. Two-week PghSD data is presented from 234 different subjects, comprising 96 healthy young middle-aged controls, 37 older men, 44 older women, 29 young adult controls and 28 sleep disorders patients in order to demonstrate the usefulness, validity and reliability of various measures from the instrument. Comparisons are made with polysomnographic and actigraphic sleep measures, as well as personality and circadian type questionnaires. The instrument was shown to have sensitivity in detecting differences due to weekends, age, gender, personality and circadian type, and validity in agreeing with actigraphic estimates of sleep timing and quality. Over a 12-31 month delay, PghSD measures of both sleep timing and sleep quality showed correlations between 0.56 and 0.81 (n = 39, P < 0.001).

Activities of Daily Living↗
PubMed1993

Age and sleep modify finger temperature responses to facial cooling.

BACKGROUND: The increased incidence of hypothermia with age suggests that healthy 80-year-olds might show impaired responsivity to transient, localized thermal stimulation. Such a deficit might be particularly clear during sleep, when behavioral thermoregulation is less likely. METHODS: We examined finger temperature cooling in response to local cooling of the face--a response presumed to be centrally mediated. Nineteen healthy 80-year-olds (12 female) and twenty-seven 20-year-olds (10 female) were exposed to repetitive 20-minute cooling and rewarming cycles across a night of sleep deprivation and a night of sleep occurring three nights later. We sought to determine whether thermal responsivity was altered by age and sleep, but by design avoided inducing core temperature hypothermia. RESULTS: In response to facial cooling during sleep deprivation, finger temperature decreased significantly more in the young than in old. This suggested relatively greater heat retention in the young. During non-REM sleep the thermal responsivity of both groups decreased and age-related differences were no longer present. Changes in core temperature induced by the stimulation were minimal. CONCLUSIONS: The results suggest that the capability of retaining heat via peripheral vasoconstriction while awake decreases with age. Despite this vulnerability, responsivity during non-REM sleep as well as average core temperature were comparable between age groups.

Adult↗
PubMed1993

Peripheral thermal responsivity to facial cooling during sleep.

A recently developed technique for examining thermal sensitivity during sleep was used to assess whether skin and core temperature responses to thermal stimulation were altered by sleep state. The technique was designed to probe thermal responsivity without altering core body temperature or inducing awakening. Twenty-seven young men and women were studied during a sleep deprivation night and a sleep night three nights later. Cold water stimulation of the face alternated with an equal period of rewarming across a 40-min cycle throughout the night. Skin temperature from the finger and rectal temperature were continuously assessed. Sleep continuity and architecture were largely uninfluenced by the thermal stimulation. Finger skin temperature decreased during cold facial stimulation in both sleep and waking states. Skin temperature changes during sleep were approximately one-fifth the magnitude of those during waking. Core temperature was minimally influenced. REM sleep was associated with a greater amplitude decrease in finger temperature than was non-REM (NREM) sleep. The results support the utility of the technique as a probe of thermal responsivity during sleep and suggest a reduction of thermal responsivity during sleep and, more tentatively, an altered responsivity during REM versus NREM sleep.

Adult↗
PubMed1993

Patterns of sleep episodes in young and elderly adults during a 36-hour constant routine.

The deterioration of nocturnal sleep and increase in daytime napping that accompany aging may represent changes in homeostatic or circadian aspects of sleep regulation. We addressed these possibilities by examining patterns of unintended sleep episodes, subjective sleepiness and mood during 36 hours of constant wakeful bed rest in 17 healthy 20-30-year-olds (n = 9 men, n = 8 women) and 18 healthy 80-year-olds (n = 11 men, n = 7 women). Subjects had continuous electroencephalographic (EEG) monitoring and core body temperature measurements and completed visual analog scale ratings of sleepiness and mood each hour. Young and elderly groups both showed significant linear and circadian trends in sleep episodes across the interval. Group x time interaction effects revealed a stronger linear trend in the young vs. elderly group, but no difference in circadian trends. Analysis of age groups by sex demonstrated more complex interactions, with elderly men showing weaker rhythmic (circadian) trends than elderly women. Subjective ratings of sleepiness and mood showed no difference in temporal trends between young and elderly groups. These data support the hypothesis that age-related sleep changes result primarily from decreases in homeostatic, rather than circadian, sleep propensity. They also confirm the presence of sex differences in sleep patterns among the elderly and support the distinction between objective and subjective measures of sleepiness.

Adult↗
PubMed1992

Electroencephalographic sleep studies in depressed outpatients treated with interpersonal psychotherapy: I. Baseline studies in responders and nonresponders.

Electroencephalographic (EEG) sleep measures have been examined as predictors of therapeutic response in patients with major depression. Although some studies have reported that EEG sleep measures are predictive of a favorable outcome with medications, two recent studies found no differences in the baseline sleep characteristics of responders and nonresponders to psychotherapy. To clarify this issue, we compared baseline EEG sleep in a group of patients with recurrent depression who responded to interpersonal psychotherapy (n = 19) and a comparable group who did not respond (n = 18). Baseline ratings of depression severity did not differ in the groups, but some differences in baseline sleep were noted. Psychotherapy nonresponders had longer sleep latencies, lower sleep efficiency, and increased automated measures of phasic rapid eye movement (REM) activity. In addition, the two groups had different EEG sleep adaptation patterns for REM latency and phasic REM density measures across the two study nights. These preliminary results suggest that baseline EEG sleep patterns, as well as the pattern of laboratory adaptation, may differ for depressed patients who respond to psychotherapy and those who do not.

Adolescent↗
PubMed1992

Electroencephalographic sleep studies in depressed outpatients treated with interpersonal psychotherapy: II. Longitudinal studies at baseline and recovery.

Electroencephalographic (EEG) sleep studies may help to identify persistent versus episodic biological characteristics of major depressive disorder. This report examines longitudinal EEG sleep studies in depressed patients treated with psychotherapy alone. Nineteen patients were studied during a symptomatic baseline period and again during early remission after treatment with interpersonal psychotherapy (IPT). EEG sleep findings at baseline were not markedly abnormal, but they were similar to those in other published studies of young adult outpatients. No changes were found in visually scored EEG sleep measures between depression and early remission. Automated measures of delta sleep and rapid eye movement (REM) activity showed small state-related changes, with delta activity increasing from baseline to remission, and automated REM measures decreasing. Strong baseline-remission correlations were noted for most sleep measures, including slow wave sleep, phasic REM activity, and automated delta EEG counts; measures of sleep continuity and tonic REM sleep were not strongly correlated. Consistent adaptation effects across nights were observed for sleep continuity and REM measures during each clinical phase. These findings support the hypothesis that most visually scored EEG sleep measures, as well as the sleep adaptation process, are stable through the acute episode of depression, at least into early symptomatic remission. They also suggest that finer-grained automated analyses of delta and REM activity may provide more sensitive tools for examining state-related changes.

Adolescent↗
PubMed1992

Rhythmic vs homeostatic influences on mood, activation, and performance in young and old men.

Nine healthy old (80+ years) men were compared with nine healthy young (20-30 years) men in a protocol that required 36 hours of continuous wakeful bedrest. Body temperature rhythm measurement confirmed that the old had as robust an endogenous circadian (approximately 24 hours) rhythm generation mechanism as the young. However, in measures of affect, activation, visual search speed, verbal reasoning speed, manual dexterity, and vigilance hit rate, the old showed a linear decline over the 36 hours of the vigil, with little of the superimposed 24-hour rhythmicity that was apparent in the young. Thus, separate from the endogenous rhythm generation processes, there appeared to be some attenuation with advanced age, which led to the relative absence of rhythmic expression in these mood and performance variables. Such attenuation might contribute to some of the sleep and performance problems reported by elderly adults.

Adult↗