REM latency and core temperature relationships in primary depression.

REM latency and rectal and ear canal temperature were studied simultaneously in 11 controls and nine depressed patients; seven of the patients were studied when recovered. REM latency was shorter in the depressed group compared with controls and lengthened with recovery. The nocturnal and ear canal temperatures were higher in the depressed group compared with controls and decreased with recovery. REM latency and the nocturnal rectal temperature were negatively correlated when all the nights of the depressed patients were analyzed (r = -0.44) and when all the nights of the subjects were analyzed (r = -0.44). REM latency and nocturnal ear canal temperatures were negatively correlated when all the nights of the control group were analyzed (r = -0.34). The timing of the temperature rhythm did not appear to be correlated with the REM latency.

Circadian temperature rhythms in young adult and aged men.

The core body temperatures of ten healthy young adult and eight healthy aged men were recorded continuously for 14-24 hours using rectal thermometers and analog tape recorders. Aged subjects had significantly higher temperatures at the nadir of the temperature curve compared to the young subjects. Cosinor analysis of the data revealed that, while all subjects' data significantly fit an idealized cosine function of 24 hours periodicity, the peak to trough amplitude of the rhythm was significantly lower in the aged group. No group differences in the 24-hour mean temperature, the mean temperature during the sleep period time, the mesor, or the acrophase were found. These data are in essential agreement with previously reported data but expand upon those findings and demonstrate that the age-related changes in amplitude of the temperature rhythm are not confined to subjects studied under isolated laboratory environments.

Plasma norepinephrine in normal young and aged men: relationship with sleep.

This study explored the relationship between age-related elevations of plasma norepinephrine (NE) levels (thought to reflect heightened sympathetic nervous system activity) and sleep. Plasma NE levels were consistently and significantly greater in 8 aged than 10 young men across a 24-hr study period. For both groups, plasma catecholamine levels remained stable near bedtimes and rise times and during spontaneous and experimentally induced nighttime awakenings; reversal of the sleep/wake pattern (nighttime wakefulness, daytime sleep) had little effect on the 24-hr plasma NE or sleep patterns, indicating that elevated NE cannot be attributed to altered sleep/wakefulness per se. The aged group had significantly more wakefulness and significantly higher plasma NE levels while in bed in all study conditions. These two variables were significantly correlated, suggesting that heightened sympathetic activity may fragment sleep with wakefulness in the aged.

Rapid eye movement sleep measures of Alzheimer's-type dementia patients and optimally healthy aged individuals.

It has been suggested that rapid eye movement (REM) sleep measures may be useful in the differential diagnosis of affective disorders. To determine what changes, if any, of REM measures occur in Alzheimer's dementia we examined the REM sleep of nine control and nine mild, nine moderate, and nine severe dementia subjects with probable Alzheimer's disease (AD). Control and mild and moderate AD groups were screened to exclude major depression. REM latency, REM time, REM activity, and REM density were examined. Results indicated that REM sleep measures are minimally affected by mild dementia. None of the REM sleep variables reported here successfully discriminated mild AD subjects from controls. However, REM time and REM latency were significantly affected in later stages of dementia. Total time in REM and REM latency successfully classified control and moderate-severe AD patients. In addition, the pattern of REM density across the night was also affected by severity of dementia. The results of this study, when compared to published REM measure findings in major depression, indicate that with proper cautions REM sleep measures may prove useful in the differential diagnosis of dementia and depression in geriatric patient populations.

Sleep apnea: relationship to age, sex, and Alzheimer's dementia.

The relationship of sleep apnea to age, sex, and Alzheimer's dementia was investigated in 45 elderly subjects and 10 young males, all nonobese, normotensive, nonsmoking, with no sleep complaints and no medical problems other than Alzheimer's disease. Mean apnea/hypopnea index [(AH)I] was significantly greater in elderly males than in young males or elderly females. Mean (AH)I and percentage of subjects with an (AH)I greater than 5 in the Alzheimer groups were not significantly different from age and sex-matched controls. Results were similar when the apnea index was substituted for (AH)I. The data from this preliminary study indicate that healthy, elderly males with no sleep complaints and elderly males with Alzheimer's disease experience a significant, subclinical ventilatory impairment during sleep. Data from the 10 elderly females and 10 young males indicated no such impairment. The physiological significance of this degree of sleep apnea in otherwise healthy elderly males is unclear at present.