The present work reviews the main individual differences which art:of
interest in the field of circadian rhythms. For this reason, and in th
e first place, the rhythmic characteristics of the following physiolog
ical parameters are presented: body temperature, blood pressure and he
art rate. In addition, data which highlight the factors that influence
the values obtained for these physiological variables from a homeosta
tic perspective-without taking into account time of day-are also outli
ned. The individual differences reviewed are the dimension of personal
ity-extroversion and neuroticism, the morningness factor, the age, the
gender and tobacco consumption. Rhythmic differences in physiological
and behavioral parameters-subjective and objective-are taken into acc
ount for each of the above variables. Although reference is also made
to the homeostatic findings liable to be considered as a function of t
ime of day.