Background: One of the most common ways to examine the daytime impact of sleep loss is the use of the psychomotor vigilance test (PVT). PVT metrics, including median reaction time (RT) and number of lapses, have been examined in a variety of studies in which both acute and chronic sleep times are manipulated. Most of these studies involve young, healthy individuals and use a visual stimulus. As light is a possible countermeasure to sleep loss, and sometimes incompatible with the use of visual PVT, PVT with auditory cues (aPVT) has been used. A threshold of 400 ms is commonly used to delineate lapses from normal RT in the aPVT. As aging can influence a variety of brain functions, we wanted to examine whether this lapse threshold was accurate for use in older adults.

Methods: Twenty-eight young and 19 healthy older participants performed a 10-min auditory PVT approximately 90 min before habitual bedtime. The occurrence of lapses was determined by five objective RT thresholds: (1) 400 ms, (2) 500 ms, (3) 2 × median, (4) mean + 2 × SD, and (5) method 4 without outliers. Results of these methods were compared with a triplicate visual inspection of RT histograms to determine RT outside of the expected log normal distribution.

Results: In both groups, methods 1, 4, and 5 performed poorly, while methods 2 and 3 were adequate, though method 3 was statistically superior.

Conclusion: In both age groups, the use of twice the median as an objective threshold had the best concurrence with visual scoring.