Frederick W. Hegge

Observations on the design and specification of a wrist-worn human activity monitoring system

Monitoring motor activity provides an important index of sleep, rest, and activity in field studies of sustained operations, shift-work schedules, and sleep deprivation. Poor results with previous methods led to development of a program to design a technologically improved monitoring system. In this 3-year program, specific issues were examined, ranging from the empirical characteristics of the wrist-movement signal and transduction methods to conversion of that signal to a useful index of motility. In this report, we discuss the several design issues encountered as well as observations, conclusions, and resulting specifications. The product of this program is a microprocessor-controlled, self-contained activity recording system, with 16K of digital storage and an operating life of over 30 days. The Walter Reed Activity Monitoring System is designed to examine further the behavioral and physiological correlates of activity.

The effects of progressive sleep loss on a lexical decision task: Response lapses and response accuracy

A lexical decision task was used in a paradigm testing the effects of sleep loss and fatigue on performance during a 72-h period of sleep deprivation. The data were partitioned into categories of response lapses, response accuracy, and the signal detection measures of discriminability (d’) and bias (β). Response lapses increased as a function of sleep loss and were fitted best by a composite equation with a major linear component and a minor rhythmic component. Response accuracy decreased as a function of sleep loss, with the rate of decrease being greater for nonwords than for words. Although d’ was higher for right visual field (RVF), it decreased for both fields almost linearly as a function of sleep deprivation. The rate of decrease for RVF stimulation was greater than for left visual field (LVF) stimulation, β did not change monotonically as a function of sleep loss, but showed strong circadian rhythmicity, indicating that it was not differentially affected by sleep loss per se.

PERCEPTUAL DISTORTIONS AND HALLUCINATIONS REPORTED DURING THE COURSE OF SLEEP DEPRIVATION

Subjects worked 30 to 45 min. of each hour for either 48 (n = 2) or 2 hr. (n = 8) without sleep. The frequency of reported visual task-related perceptual distortions and hallucinations showed both a linear increasing component and a strong circadian component. Perceptual distortions were most frequent in the late night-early morning hours (0400) and least frequent in the late afternoon-early evening hours (1600–2000).

Dynamic changes in work/rest duty cycles in a study of sleep deprivation

The effects of moderate workload and 72 h of sleep deprivation were studied using a modified continuous-performance paradigm. Ten subjects were tested hourly on a number of perceptual and cognitive tasks designed to require approximately 30 min to complete, with the remainder of each hour free. As sleep deprivation continued, the average time on task increased at an accelerating rate. The rate of increase differed among tasks, with longer tasks showing greater absolute and relative increases than shorter ones. Such increases confound sleep deprivation and workload effects. In this paper, we compare the advantages and disadvantages of several experimental paradigms; describe details of the present design; and discuss methodological problems associated with separating the interactions of sleep deprivation, workload, and circadian variation with performance.

Trend and rhythm analysis of time-series data using complex demodulation

Biological time-series data collected over long intervals generally show combined systematic and periodic fluctuations. Comprehensive analysis of such data requires separation of the trend and rhythmic components. Most available time-series analytic techniques do not explicitly extract the trend, and do implicitly assume the underlying rhythms are simple symmetrical sinusoids, whose amplitude and phase values remain constant throughout the recorded interval. Neither assumption is very accurate when dealing with biological data, and the stationarity assumption in particular becomes harder to defend as experiments extend over days or even weeks. Complex demodulation (CD) is described here as a technique for separation of trend from cyclic components, and multiple complex demodulation (MCD) as a technique for extraction of all possible frequencies in the data set, along with their moment-by-moment amplitude and phase values.

Lexical decision, parafoveal eccentricity and visual hemifield.

The effect of the eccentricity of parafoveal stimulation on a lexical decision task was studied using stimuli presented to the two visual hemifield. Five-letter word and nonword stimuli were presented to three parafoveal locations ranging over 1 degree angle of eccentricity. Subjects responded manually. The results of the analyses indicated that the average RT to words was approximately 48 msec. shorter than to nonwords. The average RT to a stimulus presented to the RVF was approximately 11 msec. shorter than to a stimulus presented to the LVF. As parafoveal location became more eccentric, RT to all stimuli increased by approximately 37 msec. per degree of eccentricity. A very significant interaction was found between the visual hemifield stimulated and the direction of response to the type of stimulus presented (word/nonword).

Acute heroin abstinence in man: II. Alterations in rapid eye movement (REM) sleep

The purpose of this study was to examine the effects of withdrawal from heroin upon rapid eye movement (REM) sleep. Subjects included both heroin-dependent patients and drug-free controls. The drug users were young males who had an average daily intake of approximately 973 mg of 92 - 98% pure heroin before entering the study. All electrophysiological data were obtained via a telemetry system on a 24-hour per day basis for 5 to 7 consecutive days. EEG records were scored into the standard awake and sleep states. Results showed a marked decrease in total amount of REM sleep during heroin withdrawal. This total decrease was associated with a decrease in duration of individual REM episodes and a large decrease in the number of occurrences of REM sleep. The heroin-dependent patients during withdrawal also showed a prolonged latency from sleep onset to first REM episode and a reduced number of REM shifts per 24-hour period. No significant difference in REM sleep interval was observed between the control subjects and drug users. Some of the overt behavioral characteristics associated with heroin withdrawal may be indirectly related to the concurrent loss in REM sleep as observed in this study.

Acute heroin abstinence in man III. Effect upon waking and slow wave sleep

The purpose of this study was to evaluate the effects of acute heroin withdrawal on waking behavior and slow wave sleep. Data were collected from drug-dependent patients who were using pure heroin and from drug-free controls. All data were recorded on a 24-hour per day basis for 5 - 7 consecutive days. EEG records were manually scored according to standard criteria. The heroin-dependent patients during withdrawal showed approximately a 26% decrease in slow wave sleep and an 18% increase in waking behavior. The awake state in the heroin-dependent patients during withdrawal also displayed an increase in number of episodes and number of state shifts, and a decrease in duration and sleep onset latency. In addition, the slow wave sleep categories during withdrawal generally showed an increase in sleep onset latency and interstate interval and a decrease in number of episodes. These results indicate that heroin withdrawal is associated with a marked disruption of the central nervous system mechanisms responsible for maintenance of the normal sleep--waking cycle. Analyses of the pattern of this disruption will further aid in understanding the withdrawal syndrome.

WinCD: Windows Software for Complex Demodulation

We describe WinCD, a program for extracting quantitative information about periodicity in time-series data using the method of complex demodulation (CD). The method is particularly well suited for the analysis of the effects of variables that may produce changes in biological rhythms, such as sleep deprivation, adaptation to changes in work schedules, time zone displacements, and various sorts of pathology. WinCD enables exploratory analysis of time series data by providing graphical displays of raw and processed time series, as well as numerous options for viewing and saving quantitative data. We describe WinCD operations and examples of the use of the program.

Acute heroin withdrawal in Viet Nam An immunochemical evaluation of excretio

Heroin use by American military personnel in Viet Nam differed from the classically reported civilian setting in the following ways: short duration, absence of medical complications, purity of drug, infrequency of concomitant drugs, and use of nasopulmonary routes rather than intravenous iniection. Urine morphine equivalent levels were assessed immunochemically (FRAT) in 10 patients and 5 controls for 15 days following withdrawal from heroin. The initial urine morphine equivalent concentration was over 20,000 ng per milliliter. Concentration declined exponentially over the first five days to fluctuating low levels thereafter. A linear relations hip between urine morphine concentration and total urinary morphine output suggests the existence of an active renal mechanism for morphine excretion. Historical assessment of heroin consumption and individual morphine excretion patterns indicated levels of opiate tolerance far higher than norrnally found in heroin‐dependent civilians.