Zulley, Jürgen

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/. Sleep Res. (1992), 1, supplement 1 FREE-RUNNING CIRCADIAN RHYTHMS IN AGING J, Zulley Max-Planck-Institute of Psychiatry, C l i n i c a l institute, Department of Psychiatry, Munich, Germany An endogenous clock system regulates a broad.set of psychological and physiological variables, leading to typical variations of the functions during the day. With aging a reduction of the circadian amplitude, a shortening of the autonomous circadian periodicity, and a weakened coupling of the variables become obvious. The latter result comes from the finding, that an increased frequency in the occurrence of internal desyn-chronization with aging has been found. Since this state i s mainly seen as an uncoupling of the rhythms by a lenghtening of the sleep-wake cycle, i t would be in contradiction to the finding of a shortening of the ryhthm. However, a reanalysis of the group of older subjects from the isolation studies under "free-run" condition in our institute, revealed that only the frequency of " i nterna1 desynchron i zat i on with shortening of the a c t i v i t y rhythm" in the older subjects increases (see figure). Since internal desynchronization and dissociation of the rhythms describes only different degrees of v a r i a b i l i t y , the main results are a remarkable decrease in the synchrony of the more unstable rhythms with a shortening of the circadian periodicity and increased tendency for ultradian rhythmicity. Such an assumption is also supported by studies in the 24-h day with a phase-advance of the sleep-wake pattern and an increased occurrence of napping. These results refer not only to sleeping and waking but have also been found in variables such as subjective alertness, body temperature, melatonin, growth hormone and Cortisol. Thus i t can be assumed, that the biological rhythms in aging show an overall increased disorganization. all subjects (n = 151 ) o l d e r s u b j e c t s 41 - 73 y. (n = 12) 8% - c i rca-bi/seml-dian rhythms desynchronization with: 8% - shortening - 42% 16% lenghtening - 8% 18% - dissociation - 83% 50% - synchronization-17% DSIP AND SLEEP STATES IN INFANTS IN THE FIRST YEAR OF LIFE G. Zwacka1. S. Scholle 1, R. Ekman2 1. University C l i n i c s , Department of Pediatrics, Jena, Germany; 2. University of Lund, Dept. Psychiatry and Neurochemistry, Lund, Sweden. Delta sleep-inducing peptide (DSIP) i s a naturally occurring nonapeptide that has been reported to a f f e c t the rhythmic organization of sleep. In the f i r s t year of l i f e sleep organiza-tion i s changing markedly. So we were interested i n plasma levels of DSIP i n the f i r s t year of l i f e i n correlation to the r a t i o of active and quiet sleep. 2 groups of children were investigated: 1. preterm infants (n=25, 28 investigations), 2. healthy full-term infants (36/37). The age of the infants ranged from -5 (postnatal age was corrected for a gestational age of 40 weeks) to 53 weeks. DSIP was radioimmuno-assayed i n plasma. A l l infants were also polygraphically i n v e s t i -gated during sleep. There was a s t a t i s t i c a l l y s i g n i f i c a n t increase of the r a t i o q u i e t / a c t i v e sleep i n dependence on age, but no c o r r e l a t i o n between the r a t i o time of active/quiet sleep and the plasma l e v e l of DSIP. The DSIP-plasma-levels were not changing i n dependence on age. In healthy full-term infants, the DSIP-level was s i g n i f i -cantly higher (median: 1885 pmol/1, interquartile range: 757 pmol/1) than i n the preterm infants (median: 1595 pmol/1, i n t e r -quartile range 385 pmol/1). The plasma l e v e l of DSIP was compa-rable to those determined by EKMAN in adults. In the f i r s t year of l i f e , DSIP plasma levels does not seem to be a marker of developmental changes of sleep pattern. 

FL: Free-running circadian rhythms in aging

http://epub.uni-regensburg.de/19932/1/ubr07606_ocr.pdf

FL: Free-running circadian rhythms in aging

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