  We present a quasi-experiment to investigate whether, and to what extent,
sleep deprivation impacts the performance of novice software developers using
the agile practice of test-first development (TFD). We recruited 45
undergraduates and asked them to tackle a programming task. Among the
participants, 23 agreed to stay awake the night before carrying out the task,
while 22 slept usually. We analyzed the quality (i.e., the functional
correctness) of the implementations delivered by the participants in both
groups, their engagement in writing source code (i.e., the amount of activities
performed in the IDE while tackling the programming task) and ability to apply
TFD (i.e., the extent to which a participant can use this practice). By
comparing the two groups of participants, we found that a single night of sleep
deprivation leads to a reduction of 50% in the quality of the implementations.
There is important evidence that the developers' engagement and their prowess
to apply TFD are negatively impacted. Our results also show that sleep-deprived
developers make more fixes to syntactic mistakes in the source code. We
conclude that sleep deprivation has possibly disruptive effects on software
development activities. The results open opportunities for improving
developers' performance by integrating the study of sleep with other
psycho-physiological factors in which the software engineering research
community has recently taken an interest in.
