0301 Different Indices of Vigilant Attention During Sleep Deprivation: Evidence of Multiple Vigilance Constructs?

Introduction

Total sleep deprivation (TSD) causes profound vigilant attention deficits, with large, trait-like individual differences, as evidenced convincingly by response lapses on the psychomotor vigilance test (PVT). There is debate, however, about the role of vigilant attention deficits in the effects of TSD on other speeded performance tasks besides the PVT. We addressed this issue by testing whether PVT response lapses are related to delays in responding to stimuli under strict deadlines in two decision making tasks.

Methods

N=54 healthy adults (aged 21-38y; 31 females) completed an in-laboratory TSD study. Following a 10h baseline sleep opportunity, cognitive testing occurred after 25h and 29h of TSD (09:00 and 13:00). Testing included an AX continuous performance task with switch (AX-CPTs), which is a dynamic decision making task requiring subjects to respond to a frequently occurring cue-probe combination; an identical pairs continuous performance task (CPT-IP), which is a 1-back go/no-go task; and a 10min PVT. Lapses (RTs>500ms) on the PVT and target accuracy on the AX-CPTs and CPT-IP were calculated as indices of vigilant attention. Intraclass correlation coefficients (ICCs) were used to quantify the stability of individual differences, and absolute rank-order correlation (|ρ|) was used to compare the three indices.

Results

The stability of individual differences ranged from fair to substantial (PVT: ICC=0.44; AX-CPTs: ICC=0.73; CPT-IP: ICC=0.31). The rank-order correlation between the AX-CPTs and CPT-IP vigilant attention indices was relatively high (|ρ|=0.44), whereas correlations with PVT lapses were much lower (AX-CPTs: |ρ|=0.14; CPT-IP: |ρ|=0.04).

Conclusion

Individual differences during TSD were moderately stable for each index of vigilant attention, but the relationships between PVT lapses and the other indices were weak. This suggests that any or all of the indices considered here are not pure measures of vigilant attention, or that vigilant attention may constitute multiple, distinct constructs.

Support

CDMRP grant W81XWH-16-1-0319

0208 The Effect of Mastication on Psychomotor Vigilance Performance

Introduction

Sustained attention is important for optimal neurobehavioral performance, but many biological and environment factors (e.g., circadian rhythm, distraction) may cause sustained attention deficits. Mastication (chewing) has been suggested to provide a countermeasure to sustained attention deficits. To investigate this, we conducted a randomized, within-subjects, cross-over study of sustained attention with a mastication condition and a control condition.

Methods

N=58 adults (ages 18–45; 38 females) completed a 5h in-laboratory study. Subjects entered the laboratory at 09:00. Following training on performance tasks, they had a 1h break before beginning the first of two test bouts at 11:00. Each test bout was 40min long and included subjective rating scales, the Sustained Attention to Response Task, and the Psychomotor Vigilance Test (PVT). Here we focus on PVT lapses of attention (RT > 500 ms), false starts, and mean reaction time (RT) as measures of sustained attention. In between test bouts, subjects had a 1h break inside the laboratory. During one of the two test bouts, subjects were instructed to chew a piece of gum at a steady, comfortable rate. Mastication activity was verified via electromyography (EMG). Half of the sample was assigned to the mastication condition during the first test bout, the other half during the second test bout.

Results

Controlling for order of conditions, there were no significant differences between conditions for PVT lapses (F1,56=0.40, P=0.54) or false starts (F1,56=0.10, P=0.80). Mean RT was higher in the mastication condition by 8.9±2.5ms (F1,56 =12.68, P<0.001).

Conclusion

Using this test paradigm, we were unable to detect any significant improvement in PVT performance, although mastication resulted in a very small increase in mean RT. However, subjects were not sleep-deprived, distracted, or otherwise perturbed. A follow-up study under conditions of sleep deprivation and/or with longer task duration may provide further insight into the countermeasure potential of mastication.

Support

Mars Wrigley Confectionery, U.S., LLC

0332 Effect of Prior Sleep Duration on Distinct Measures of Daytime Cognitive Performance in Late Adolescence

Introduction

A recent longitudinal study of sleep need changes across adolescence reported how prior sleep duration affects daytime sleepiness and vigilant attention in children ages 10-16 years. In a follow-up study, we extend the age range in a new group of participants and add additional performance tests. Here we report year 1 data on the effect of systematically varied time in bed (TIB) on daytime vigilance, working memory, and decision making.

Methods

Data are for 52 participants aged 15.0-20.4 years (mean±SD: 17.7±1.8 years). Annually, participants keep each of three different TIB schedules: 7h, 8.5h or 10h TIB for 4 consecutive nights. The 4th night is followed by a laboratory day of performance testing. The day includes four 10-minute psychomotor vigilance tests (PVT); a serial position Sternberg working memory task; and an AX continuous performance test with switch (AX-CPTs) measuring cognitive flexibility in decision making.

Results

PVT performance evaluated by the log of the signal to noise ratio (LSNR) improved monotonically with increasing TIB (p<0.0001). TIB also affected serial position Sternberg task accuracy (p=0.008) but not the probe position effect (p=0.66), indicating that TIB did not affect working memory. TIB also affected AX-CPTs accuracy (p<0.0001), but TIB did not significantly affect decision making and cognitive flexibility measures extracted from this task (all p>0.09).

Conclusion

The initial data from this longitudinal study on older adolescents confirm what we observed for younger adolescents. Increasing TIB improves daytime vigilance but does not affect working memory. These initial results also do not indicate a TIB related improvement in decision making. Data from the entire three year longitudinal study will allow us to further investigate relations of performance to prior sleep duration and whether these relations change with age. Results from dose-response studies such as these can help guide sleep duration recommendations.

Support

PHS grant R01 HL116490 supported this work.