Psychomotor slowness is associated with self-reported sleep duration among the general population

Short and long self-reported sleep durations have been found to be associated with several seemingly disparate health risks and impaired functional abilities, including cognitive functioning. The role of long sleep is especially poorly understood in this context. Psychomotor slowness, shown to have analogous associations with cognitive performance and health risks as self-reported long sleep duration, has not been studied together with sleep duration in epidemiological settings. We hypothesized that self-reported habitual sleep duration, especially long sleep, is associated with slow psychomotor reaction time, and that this association is independent of vigilance-related factors. The hypothesis was tested in a sample of 5352 individuals, representing the general adult population. We found a U-shaped association between self-reported sleep duration and psychomotor speed, which prevailed even after controlling for several pertinent confounders. This novel finding can be interpreted to mean that self-reported sleep duration, at least in the case of long sleep, is an indicator of bodily/brain integrity and, taken together with the results of cognitive epidemiology, may provide some new insights into the mechanisms underlying the associations between habitual self-reported sleep duration, health risks and impaired functional abilities.