Journal of Applied Physiology, Vol 80, Issue 1 14-19, Copyright © 1996 by American Physiological Society
Sleep in monozygotic twin pairs discordant for obesity
E. Kronholm, S. Aunola, M. T. Hyyppa, M. Kaitsaari, M. Koskenvuo, C. E. Mattlar and T. Ronnemaa
Research and Development, Social Insurance Institution, Turku, Finland.
Nocturnal motor breathing and cardiac activity were recorded by using the
static charge-sensitive bed, and sleep habits were studied by questionnaire
in 24 pairs of monozygotic twins discordant for their body mass index; the
mean intrapair difference between co-twins was 6.7 kg/m2. Intrapair
differences in sleep characteristics between co-twins were related to
intrapair differences in physiological and anthropometric characteristics.
Two questions were tested. First, do monozygotic twins discordant for body
mass index differ in sleep behavior? Second, if they do, are differences in
sleep associated with nongenetic differences in the body weight and
metabolism or with other environmental factors? Obese twins had higher
nocturnal motor activity levels, less quiet sleep, and more habitual
snoring than did their nonobese co-twins. Differences in sleep were
associated with obesity-related factors. However, habitual snoring did not
explain other intrapair differences in sleep. It was concluded that
relatively moderate obesity is associated with disruption of physiological
structure of sleep as measured by the static charge-sensitive bed method
and that this disruption seems not to be associated with snoring or
breathing disturbances.
