/. 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 i n 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 i s 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% - circa-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 L I F E G. Zwacka1. S. S c h o l l e1, R. Ekman2
1. U n i v e r s i t y C l i n i c s , Department of P e d i a t r i c s , Jena, Germany;
2. U n i v e r s i t y o f Lund, Dept. P s y c h i a t r y and Neurochemistry, Lund, Sweden.
D e l t a s l e e p - i n d u c i n g peptide (DSIP) i s a n a t u r a l l y o c c u r r i n g n o n a p e p t i d e t h a t has been r e p o r t e d t o a f f e c t t h e r h y t h m i c o r g a n i z a t i o n o f s l e e p . I n the f i r s t y e a r o f l i f e s l e e p o r g a n i z a - t i o n i s changing markedly. So we were i n t e r e s t e d i n plasma l e v e l s of DSIP i n t h e f i r s t year of l i f e i n c o r r e l a t i o n t o t h e r a t i o o f a c t i v e and q u i e t s l e e p .
2 groups o f c h i l d r e n were i n v e s t i g a t e d : 1. preterm i n f a n t s (n=25, 28 i n v e s t i g a t i o n s ) , 2. h e a l t h y f u l l - t e r m i n f a n t s (36/37). The age of t h e i n f a n t s ranged from -5 ( p o s t n a t a l age was c o r r e c t e d f o r a g e s t a t i o n a l age o f 40 weeks) t o 53 weeks. DSIP was radioimmuno- assayed i n plasma. A l l i n f a n t s were a l s o p o l y g r a p h i c a l l y i n v e s t i - gated d u r i n g s l e e p .
T h e r e 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 i n c r e a s e o f t h e r a t i o q u i e t / a c t i v e s l e e p i n dependence on age, b u t no c o r r e l a t i o n between t h e r a t i o time o f a c t i v e / q u i e t s l e e p and t h e plasma l e v e l of DSIP. The DSIP-plasma-levels were not changing i n dependence on age. I n h e a l t h y f u l l - t e r m i n f a n t s , t h e D S I P - l e v e l was s i g n i f i - c a n t l y h i g h e r (median: 1885 pmol/1, i n t e r q u a r t i l e range: 757 pmol/1) than i n t h e preterm i n f a n t s (median: 1595 pmol/1, i n t e r - q u a r t i l e range 385 pmol/1). The plasma l e v e l o f DSIP was compa- r a b l e t o those determined by EKMAN i n a d u l t s .
In t h e f i r s t year of l i f e , DSIP plasma l e v e l s does n o t seem t o be a marker o f developmental changes o f s l e e p p a t t e r n .
