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Biomedical subjects

D F Kripke

Publications and source records attributed to D F Kripke.

At least 109 records · Page 6Linked to original sources
PubMed1984

Theophylline delays human sleep phase.

Twelve healthy male volunteers were given theophylline 250 mg in order to test effects on 24-hr rhythms. Rhythms of sleep/wake and subjective sleepiness were delayed. Ingestion of xanthines such as theophylline in coffee, tea, colas and chocolate may contribute to some sleep disorders. Theophylline might likewise be useful in treating disorders of circadian oscillators.

Adult↗
PubMed1984

Critical interval hypotheses for depression.

Two chronobiologic models are presented for the etiology of depression. The internal coincidence model suggests that a phase advance of the strong oscillator in reference to the weak oscillator causes depression. An external coincidence model suggests that depression is caused when the light/dark cycle or photoperiod provides too little illumination during a critical photosensitive interval, which might in turn occur early due to a phase advance. Thus, depression might be treated by drugs or other manipulations which delay the phase of internal circadian rhythms. Depression might also be treated with bright illumination during the critical photosensitive interval. Preliminary experiments suggest that bright artificial light does have antidepressant effects. The optimal times for light exposure and the most responsive patient groups have not yet been identified.

Animals↗
PubMed1984

Effects of a single dose of flurazepam on the sleep of healthy volunteers.

We compared the effects of a single dose of flurazepam (Dalmane) 45 mg with placebo on the sleep of twelve young, healthy male volunteers. A double-blind random-order cross-over design was used. Flurazepam 45 mg had no effect on sleep latency to stage 1 or to stage 2 sleep and no effect on percent stages 3 and 4 sleep. Total sleep time and percent stage 2 sleep significantly increased on the drug night, while wake time, percent stage 1, and percent REM decreased. It is hypothesized that decreases in stages 3 and 4 that are generally seen on second administration or withdrawal of flurazepam are due to the major metabolite, N-desalkyl-flurazepam. In addition, respiration was recorded in six subjects. The number of NREM apneas increased from 15 on the placebo night to 29 on the drug night, although this was not statistically significant. The effect of flurazepam and other benzodiazepines on respiration deserves further study.

Adolescent↗
PubMed1983

Bright white light alleviates depression.

Studies of biological rhythm disorders among manic-depressive patients have suggested that depressed patients may have an early photosensitive interval. If so, exposure to bright light during the photosensitive interval might relieve depressive symptoms. As a test of this hypothesis, 12 depressed patients were exposed to bright white light from roughly 5 to 6 a.m. On the afternoon following this treatment, depressive symptoms were reduced in comparison to baseline ratings and as compared to afternoons following similar exposures to dim red light.

Arousal↗
PubMed1983

Why we need a tax on sleeping pills.

In the United States every year the total costs of giving sleeping pills can be estimated at $500 million to $1 billion. Many if not most of the prescriptions are inappropriate. Sleeping pill use, associated with a 50% increase in overall mortality, is especially dangerous for older people, who have a high risk of sleep apnea. There is virtually no evidence that sleeping pills are effective with prolonged usage and no evidence for life-preserving benefits. Excessive use of sleeping pills should be discouraged with a tax of 4 per pill. Revenues from the tax should fund new research to determine which sleeping pills are safest and when alternative treatments are safer.

Cost-Benefit Analysis↗
PubMed1983

Naturalistic studies of human light exposure.

For 24 h, 10 volunteers wore an apparatus that recorded their exposure to light at eye level and at the wrist. Activity was also recorded from the head, both wrists, and an ankle. Most of the subjects were exposed to daylight illumination intensities for only brief and scattered episodes during the 24 h. Some experienced the brightest illumination in the morning and others in the evening. Illuminations at eye level and at the wrist were correlated 0.76, while eye-level illumination was correlated 0.25, 0.44, 0.39, and 0.44 with head, wrists, and ankle activity, respectively. Because human biologic rhythms are probably well synchronized only by illumination approaching daylight intensities, inadequate illumination could be a source of sleep disturbance, chronobiologic disorders, or depression.

Adult↗
PubMed1983

Sleep apnea: a prospective study.

Sleep apnea is remarkably prevalent among general medical patients. Of 26 men randomly selected on a Veterans Administratin hospital medical ward, with a mean age of 66.2 (SD=11.5) years, 7 (27%) had sleep apnea. Of concern is that two of the seven patients were receiving hypnotic drugs. Portable sleep recordings may need to be done when routinely assessing elderly medical patients.

Adult↗
PubMed1982

The interaction of lithium and time-of-day on calcium, magnesium, parathyroid hormone, and calcitonin in rats.

Effects of lithium on the concentrations and temporal patterns of serum and cerebellar calcium and magnesium, parathyroid hormone, and calcitonin were studied in 186 rats sacrificed around 24 hours of clock time. Serum calcium, serum and cerebellar magnesium, and parathyroid hormone were increased and calcitonin decreased in lithium-fed animals. Lithium-fed rats also showed different temporal patterns in serum calcium, parathyroid hormone, cerebellar magnesium, and calcitonin. Data support the hypothesis that lithium competes for calcium receptor sites, causing a compensatory increase in parathyroid hormone and decrease in calcitonin until a new, higher set-point for calcium is established. Lithium strongly affected biological rhythms, an effect which may account in part for the diverse literature on lithium's influence on calcium and magnesium regulation.

Animals↗
PubMed1982

Sleep apnea and nocturnal myoclonus in the elderly.

Insomnia, daytime sleepiness, and nocturnal wandering, so common in the elderly, are caused largely by two specific pathophysiologic processes. Sleep apnea is a condition where respiration pauses during sleep, leading to arousal. Sleep apnea is due either to obstruction in the throat or failure of the central respiratory center. Periodic movements in sleep are characterized by frequent ankle and leg flexions, leading to arousal. Sleep apnea and periodic movements in sleep require specific diagnoses and treatments. Each process occurs in 20%-30% of people over 65, and perhaps the majority of older people have one or the other condition or both. Because of possible interactions with these sleep disorders, the widespread prescribing of sleeping pills to elderly patients is irrational and often dangerous. In the future, large-scale clinical trials will be needed to define effective long-term treatments for these conditions and to define when treatment is worthwhile.

Aged↗
PubMed1982

An activity-based sleep monitor system for ambulatory use.

Wrist activity measured with a piezoceramic transducer was digitized and analyzed together with subjects' sleep/wake status to derive an optimal method for automatic computer sleep/wake scoring. Several algorithms for quantifying periods of activity were considered, and an algorithm that summed changes in activity level over a 2-s interval was found most sensitive. A computer program for scoring sleep/wake from the resulting digital activity records was then developed, and parameters derived by comparison with subjects' sleep/wake status as determined by EEG. EEG and activity sleep/wake scores agreed 94.46% of the time. A further prospective test of the automatic scoring system with new data yielded agreement of 96.02%. Finally, the data collection and recording functions were implemented in a wearable microprocessor-based digital activity monitor. The automatic scoring program was adjusted to use activity data collected by this monitor, and agreed 93.88% with EEG scoring. A prospective test with new data agreed 93.04% with EEG. Automatic scoring of activity data for sleep/wake is not only fast and accurate, but allows sleep to be monitored in non-laboratory situations. In addition, the score is objective and reliable, and free of scorer bias and drift.

Computers↗
PubMed1982

Lithium delays biochemical circadian rhythms in rats.

Recent evidence has indicated that a fast circadian oscillator or pacemaker might contribute to affective illnesses, particularly manic depressive disease. In order to test the hypothesis that lithium exerts its therapeutic effect by slowing or delaying overly fast circadian rhythms, 95 rats were fed a lithium-containing diet for a period of 3-4 weeks, and 91 rats were fed a control diet. The animals were sacrificed at times around the clock. Eight of the eleven substances measured (plasma prolactin, PTH, corticosterone, and aldosterone, serum calcium and magnesium, and cerebellar calcium and magnesium) showed large delays in their circadian rhythms in the lithium-fed rats. This supports the hypothesis that lithium's therapeutic action is to delay overly fast circadian rhythms.

Animals↗