This paper reviews studies which have dealt with the relationship betw
een morningness-eveningness (circadian typology) and other individual
differences such as age, sex, personality dimensions and work schedule
of their subjects. It appeared that the changes in the morningness-ev
eningness preference covaried with the age related changes in the inte
rnal body clock. An older age was associated with morningness while yo
unger subjects tended towards eveningness, the critical age for the ci
rcadian typology change was 50 years. Sex-related differences are too
small to be reflected in the scores on circadian typology questionnair
es, although women were ahead of men by 1 hr in their circadian rhythm
s. The results on work schedule proved its role as a synchronizer modi
fying the morningness factor. The morningness dimension and extraversi
on are probably related through the impulsivity subdimension, which is
closely associated with brain activation. Further research is needed
to clarify the relationship between morningness and other personality
dimensions (neuroticism, psychoticism), because the results are inconc
lusive. The influence of circadian typology on the tolerance to shift
work and life habits are also discussed. The results with regard to sh
ift work revealed the importance of morningness in determining human t
olerance and health complaints. As regards life habits, there were dif
ferences in various aspects related to circadian typology especially p
sychoactive substances consumption.