Acute Effects of Sleep Deprivation on Ocular-Motor Function as Assessed by King-Devick Test Performance

Abstract

Less than 10% of high school and college student-athletes obtain the recommended amount of sleep each night. Ocular-motor function, specifically saccade movement, is known to be negatively affected by sleep deprivation. The King-Devick Test is a concussion assessment tool that measures neurocognitive and saccadic function. However, how one’s King-Devick Test performance is affected by sleep deprivation remains unknown. Thus, the purpose of this study was to investigate the acute effects of sleep deprivation on ocular-motor function as assessed by the King-Devick Test. We hypothesized that those who were sleep deprived would have an increased, or worsened time performance in the King-Devick Test compared to those in the control group.

Forty-two college-aged subjects (18-26 years old) who regularly slept 7-9 hours per night and had normal or corrected-to-normal vision were recruited in the study. Exclusion criteria were any sleep disorders or neurocognitive dysfunctions, and pregnant females. Participants were randomly assigned to one of 2 groups: control and sleep deprivation. One week prior to testing, participants were fitted with an ActiGraph and given a sleep log to objectively and subjectively record sleep durations, respectively. There were 3 test sessions with 1 intervention over a 24-hour period: Test 1 (7am), Test 2 (7pm), overnight sleep intervention, Test 3 (7am). King-Devick measurements of time in seconds and cumulative errors made were recorded for each test session. Individuals in the sleep deprivation group underwent sleep restriction of 3.5 hours during the intervention while the control group slept 8 hours. A repeated measures analysis of variance was used to identify a significant time by group interaction as well as main effect for time. Further investigation using Bonferroni post-hoc testing allowed insight to the significant difference(s) that occurred. Data were analyzed using SPSS Statistics Version 23 and level of statistical significance was set to P< 0.05.

The repeated measures analysis of variance showed that there was a statistically significant Group x Time interaction for King-Devick speed, [F(1.7,67.6)=8.840, p=0.001], and showed significant main effect for time [F(1.7,67.6)=12.736, p <0.001]. Bonferroni post-hoc analysis revealed that the control group continued to improve their saccadic performance over time [Time 1 (42.0$\pm$4.4), Time 2 (40.2$\pm$4.2), Time 3 (38.4$\pm$4.2); Time 1 vs. 2, p<0.001; Time 1 vs. 3, p<0.001; Time 2 vs. 3, p=0.028], while such improvement was not seen in the sleep deprivation group after acute sleep deprivation [Time 1 (41.3$\pm$5.8), Time 2 (38.7$\pm$6.0), Time 3 (40.9$\pm$7.3): Time 1 vs. 2, p<0.001; Time 1 vs. 3, p=1.00; Time 2 vs. 3, p=0.002].

In conclusion, acute sleep deprivation mitigates learning effect seen in the control group, indicating that acute sleep deprivation may cause substantial decrease in neuro-ophthalmologic efficiency. Sleep deprivation negatively impacts ocular-motor function, specifically saccadic movement, as illustrated by regressing expected learning curve in the King-Devick perfromance in the sleep deprivation group. Relying on saccades and cognitive function, the King-Devick Test is a commonly used concussion assessment tool. The result has an immense clinical implication because administering the King-Devick Test to someone in a sleep deprived condition may falsify the results. A baseline test could be inaccurately high which, when compared to a post-injury result, may create a false negative. Further, a post-injury test in a sleep deprived condition may increase the performance time even in the absence of a concussion leading to a false positive.