Paradoxical effects from stimulus density manipulation provide new insight into the impact of sleep deprivation on...

The psychomotor vigilance test (PVT), a 10-min one-choice reaction time task with random response-stimulus intervals (RSIs) between 2 and 10 s, is highly sensitive to behavioral alertness deficits due to sleep loss. To investigate what drives the performance deficits, we conducted an in-laboratory total sleep deprivation (TSD) study and compared performance on the PVT to performance on a 10-min high-density PVT (HD-PVT) with increased stimulus density and truncated RSI range between 2 and 5 s. We hypothesized that the HD-PVT would show greater impairments from TSD than the standard PVT.

n = 86 healthy adults were randomized (2:1 ratio) to 38 h of TSD (n = 56) or corresponding well-rested control (n = 30). The HD-PVT was administered when subjects had been awake for 34 h (TSD group) or 10 h (control group). Performance on the HD-PVT was compared to performance on the standard PVTs administered 1 h earlier and 1 h later.

The HD-PVT yielded approximately 60% more trials than the standard PVT. The HD-PVT had faster mean response times (RTs) and equivalent lapses (RTs > 500 ms) compared to the standard PVT, with no differences between the TSD effects on mean RT and lapses between tasks. Further, the HD-PVT had a dampened time-on-task effect in both the TSD and control conditions.

Contrary to expectation, the HD-PVT did not show greater performance impairment during TSD, indicating that stimulus density and RSI range are not primary drivers of the PVT's responsiveness to sleep loss.