A meta-analysis of the impact of short-term sleep deprivation on cognitive variables

Abstract

A substantial amount of research has been conducted in an effort to understand the impact of short-term (<48 hr) total sleep deprivation (SD) on outcomes in various cognitive domains. Despite this wealth of information, there has been disagreement on how these data should be interpreted, arising in part because the relative magnitude of effect sizes in these domains is not known. To address this question, we conducted a meta-analysis to discover the effects of short-term SD on both speed and accuracy measures in 6 cognitive categories: simple attention, complex attention, working memory, processing speed, short-term memory, and reasoning. Seventy articles containing 147 cognitive tests were found that met inclusion criteria for this study. Effect sizes ranged from small and nonsignificant (reasoning accuracy: g = -0.125, 95% CI [-0.27, 0.02]) to large (lapses in simple attention: g = -0.776, 95% CI [-0.96, -0.60], p < .001). Across cognitive domains, significant differences were observed for both speed and accuracy; however, there were no differences between speed and accuracy measures within each cognitive domain. Of several moderators tested, only time awake was a significant predictor of between-studies variability, and only for accuracy measures, suggesting that heterogeneity in test characteristics may account for a significant amount of the remaining between-studies variance. The theoretical implications of these findings for the study of SD and cognition are discussed.

Figure 1

Forest plots for a sample cognitive domain (lapses in simple attention tests). Effect sizes and 95% confidence intervals are plotted for the effect of short-term sleep deprivation on lapses in tests of simple attention. See the supplemental materials file for references to the studies cited here.

Figure 2

Forest plots for a sample cognitive domain (reaction times in simple attention tests). Effect sizes and 95% confidence intervals are plotted for the effect of short-term sleep deprivation on reaction times in tests of simple attention. See the supplemental materials file for references to the studies cited here.

Figure 3

Illustration of two possible ways in which sleep deprivation (SD) can affect speed and accuracy variables. Two sources of change may potentially occur following a period of total SD: a downward shift of the performance curve and a movement along the curve. In the case where δ₁ = δ₂ (i.e., there is a move to point S₁), no bias toward speed or accuracy occurs following SD. A movement along the curve (i.e., to S₂), however, would represent not just an overall decrement in performance but also a bias toward more accurate responding.