Figure 3.

Psychomotor Vigilance Test (PVT) response speed analyses. A 3-minute PVT was performed each morning in the hospital (average time PVT was taken was 07:56 am). Higher response speed values reflect faster reaction times on the PVT and higher levels of alertness. The 3/s starting point of the ordinate was chosen as 97% of the observed response speed values fell above this value. Error bars reflect standard errors (SE). (A) PVT response speed was significantly slower in interns after on-call nights compared to all other shifts (all p < .001). (B) PVT response speed in interns depending on minutes elapsed after waking up and relative to those who did not sleep in the 12 hours prior to PVT administration. Response speed was lowest in those who did not sleep at all. In those who did sleep on-call, response speed was decreased in the first hour after waking up due to sleep inertia. It did not differ significantly during this first hour compared to response speed of interns who did not sleep at all (p > .18). (C) PVT response speed in interns and residents increased strictly monotonic with sleep obtained in the 12 hours prior to PVT administration. It was lowest in those who did not sleep at all (0 hours).