  Circadian rhythms are the cycles of our internal clock that play a key role
in governing when we sleep and when we are active. A related concept is
chronotype, which is a person's natural tendency toward activity at certain
times of day and typically governs when the individual is most alert and
productive. In this work we investigate chronotypes in the setting of an
Introductory Computer Programming (CS1) course. Using keystroke data collected
from students we investigate the existence of chronotypes through unsupervised
learning. The chronotypes we find align with those of typical populations
reported in the literature and our results support correlations of certain
chronotypes to academic achievement. We also find a lack of support for the
still-popular stereotype of a computer programmer as a night owl. The analyses
are conducted on data from two universities, one in the US and one in Europe,
that use different teaching methods. In comparison of the two contexts, we look
into programming assignment design and administration that may promote better
programming practices among students in terms of procrastination and effort.
