AJP - Regulatory, Integrative and Comparative Physiology, Vol 264, Issue 6 1077-R1083, Copyright © 1993 by American Physiological Society
Influence of endotoxin on nocturnal sleep in humans
T. Pollmacher, W. Schreiber, S. Gudewill, H. Vedder, K. Fassbender, K. Wiedemann, L. Trachsel, C. Galanos and F. Holsboer
Max Planck Institute of Psychiatry, Department of Psychiatry, Munich, Federal Republic of Germany.
Sleepiness is a common complaint during infectious diseases, but the
interaction between sleep and host defense mechanisms has been poorly
explored in humans. We therefore studied the effect of endotoxin, a major
pathophysiological factor in gram-negative bacterial infections, on sleep
and on parameters of the primary host response in men. In a single-blind
counterbalanced trial, 15 healthy volunteers received either placebo or
Salmonella abortus equi endotoxin (0.4 ng/kg body wt) intravenously on two
separate occasions. Nocturnal sleep was recorded, and rectal temperature
and the plasma levels of tumor necrosis factor-alpha, interleukin-6,
adrenocorticotropic hormone, and cortisol were monitored for 12 h.
Endotoxin reduced the relative amounts of wakefulness (P < 0.05) and
rapid-eye-movement (REM) sleep (P < 0.05) and increased the relative
amount of non-REM sleep (P < 0.01). Electroencephalogram delta power
during non-REM sleep, as measured by spectral analysis, was not altered by
endotoxin. The endotoxin-induced changes in sleep structure were related
temporally and quantitatively to the increases in rectal temperature and to
the release of cytokines and neurohormones. It is concluded that cytokines
and neurohormones mediate the effects of endotoxin upon sleep. The ensuing
increase in non-REM sleep may be part of the adaptive host response to
bacterial infections in humans.
