Effect of birth season on circadian typology appearing in Japanese young children aged 2 to 12 years disappears in older students aged 18 to 25 years.

Several studies suggest that season of birth differentially affects the physiological characteristics of humans. Those living at relatively high latitude, such as Canada, Spain, and Italy (44°N-45°N), and born in the fall tended to be "morning-type" persons in comparison to those born in other seasons. There are relatively little data on the affect of season of birth on people residing at low latitude.