Cornell University Medical College, 420 East 70th Street, New York, NY 10021 USA.
Short-term memory, alertness and performance: a reappraisal of their relationship to body temperature
Article first published online: 20 JAN 2009
© 1992 European Sleep Research Society
Journal of Sleep Research
Volume 1, Issue 1, pages 24–29, March 1992
How to Cite
JOHNSON, M. P., DUFFY, J. F., DIJK, D. J., RONDA, J. M., DYAL, C. M. and CZEISLER, C. A. (1992), Short-term memory, alertness and performance: a reappraisal of their relationship to body temperature. Journal of Sleep Research, 1: 24–29. doi: 10.1111/j.1365-2869.1992.tb00004.x
- Issue published online: 20 JAN 2009
- Article first published online: 20 JAN 2009
- Accepted in revised form 13 December 1991; received 1 November 1991
- body temperature;
- circadian rhythm;
- short-term memory
SUMMARY Previous studies have led to the beliefs: (1) that short-term memory is best during the night when the body temperature is at its nadir, and (2) that the circadian rhythms of short-term memory and subjective alertness are driven by oscillators independent from each other and from the body temperature cycle. Unfortunately, these conclusions, which would have major implications for understanding the organization of the human circadian timing system, are largely based on field and laboratory studies, which in many cases sampled data infrequently and/or limited data collection to normal waking hours. In order to investigate these points further, we have monitored behavioural variables in two different protocols under controlled laboratory conditions: (1) during a period of 36–60 h of sustained wakefulness; and (2) during forced desynchrony between the body temperature and sleep/wake cycles, allowing testing of non-sleep-deprived subjects at all circadian phases. Contrary to earlier findings, we report here that the circadian rhythm of short-term memory varies in parallel with the circadian rhythms of subjective alertness, calculation performance, and core body temperature under both these experimental conditions. These results challenge the notion that short-term memory is inversely linked to the body temperature cycle and suggest that the human circadian pacemaker, which drives the body temperature cycle, is the primary determinant of endogenous circadian variations in subjective alertness and calculation performance as well as in the immediate recall of meaningful material.