Samantha M. Riedy

3-minute smartphone-based and tablet-based psychomotor vigilance tests for the assessment of reduced alertness due to sleep deprivation

The psychomotor vigilance test (PVT) is widely used to measure reduced alertness due to sleep loss. Here, two newly developed, 3-min versions of the psychomotor vigilance test, one smartphone-based and the other tablet-based, were validated against a conventional 10-min laptop-based PVT. Sixteen healthy participants (ages 22–40; seven males, nine females) completed a laboratory study, which included a practice and a baseline day, a 38-h total sleep deprivation (TSD) period, and a recovery day, during which they performed the three different versions of the PVT every 3xa0h. For each version of the PVT, the number of lapses, mean response time (RT), and number of false starts showed statistically significant changes across the sleep deprivation and recovery days. The number of lapses on the laptop was significantly correlated with the numbers of lapses on the smartphone and tablet. The mean RTs were generally faster on the smartphone and tablet than on the laptop. All three versions of the PVT exhibited a time-on-task effect in RTs, modulated by time awake and time of day. False starts were relatively rare on all three PVTs. For the number of lapses, the effect sizes across 38xa0h of TSD were large for the laptop PVT and medium for the smartphone and tablet PVTs. These results indicate that the 3-min smartphone and tablet PVTs are valid instruments for measuring reduced alertness due to sleep deprivation and restored alertness following recovery sleep. The results also indicate that the loss of sensitivity on the 3-min PVTs may be mitigated by modifying the threshold defining lapses.

Validation of a portable, touch-screen psychomotor vigilance test

INTRODUCTIONnThe Psychomotor Vigilance Test (PVT) measures effects of fatigue from sleep loss and circadian misalignment on sustained vigilance performance. To promote PVT use in field environments, a 5-min PVT version has been implemented on a personal digital assistant (PDA) with a touch screen. The present laboratory study was conducted to validate this PVT against a standard 10-min laptop PVT across 38 h of total sleep deprivation (TSD).nnnMETHODSnFollowing a baseline sleep night, subjects underwent 38 h of TSD, during which they performed the PVT every hour, alternating between the two test platforms. The study concluded with a night of recovery sleep.nnnRESULTSnThe primary outcome was the number of PVT lapses (reaction times > 500 ms). Both PVT platforms showed significant effects for the number of lapses across TSD test times involving an increase with time awake modulated by circadian rhythm. Laptop PVT lapses across test times exhibited a large effect size (f2 = 0.36), whereas PDA PVT lapses exhibited a medium effect size (f2 = 0.17). The laptop PVT showed a significant effect for the number of false starts during TSD similar to the temporal profile of lapses, while the PDA PVT had false starts throughout the TSD period.nnnDISCUSSIONnThe 5-min PDA PVT provided performance testing functionality and results comparable to the 10-min laptop PVT. The number of PDA PVT lapses tracked fatigue similarly to the laptop PVT lapses, albeit with smaller average ranges and effect sizes.

Normal sleep requires the astrocyte brain-type fatty acid binding protein FABP7

The astrocyte brain-type fatty acid binding protein FABP7 regulates sleep consolidation across phylogeny. Sleep is found widely in the animal kingdom. Despite this, few conserved molecular pathways that govern sleep across phyla have been described. The mammalian brain-type fatty acid binding protein (Fabp7) is expressed in astrocytes, and its mRNA oscillates in tandem with the sleep-wake cycle. However, the role of FABP7 in regulating sleep remains poorly understood. We found that the missense mutation FABP7.T61M is associated with fragmented sleep in humans. This phenotype was recapitulated in mice and fruitflies bearing similar mutations: Fabp7-deficient mice and transgenic flies that express the FABP7.T61M missense mutation in astrocytes also show fragmented sleep. These results provide novel evidence for a distinct molecular pathway linking lipid-signaling cascades within astrocytes in sleep regulation among phylogenetically disparate species.

Sleep quality, sleepiness and the influence of workplace breaks: A cross-sectional survey of health-care workers in two US hospitals

ABSTRACT This study assessed sleep quality, sleepiness and use of workplace break opportunities in 1285 health-care workers via an online questionnaire. Two hospitals were surveyed – one with and one without a fatigue mitigation policy. Across all respondents, 68.9% reported generally taking breaks of at least 30 min and 21.7% had access to a quiet place to rest, with no significant differences between hospitals. The presence of a fatigue mitigation policy was not associated with reduced sleepiness. However, accounting for hospital and shift characteristics, employees with access to a quiet place to rest while on break had significantly lower self-reported sleepiness scores.

Cognitive performance and self-reported sleepiness are modulated by time-of-day during a mountain ultramarathon

ABSTRACT Ninety-two runners completed the study during a 168 km mountain ultramarathon (MUM). Sleepiness, self-reported sleep duration, and cognitive performance were assessed the day before the race and up to eight checkpoints during the race. Sleepiness was assessed using the Karolinska Sleepiness Scale. Cognitive performance was also assessed using the Digital Symbol Substitution Task (DSST). Runner reported 23.40 ± 22.20 minutes of sleep (mean ± SD) during the race (race time: 29.38 to 46.20 hours). Sleepiness and cognitive performance decrements increased across this race, and this was modulated by time-of-day with higher sleepiness and greater performance decrements occurring during the early morning hours. Runners who slept on the course prior to testing had poorer cognitive performance, which may suggest that naps on the course were taken due to extreme exertion. This study provides evidence that cognitive performance deficits and sleepiness in MUM are sensitive to time into race and time-of-day.