BALTIMORE—Levels of peripheral microRNAs (miRNAs) change in response to total sleep deprivation (TSD) and psychologic stress, according to a study described at the 32nd Annual Meeting of the Associated Professional Sleep Societies. The molecules also predict individual differences in cognitive performance following these conditions. The results suggest that miRNAs can “identify individuals ahead of time who are in need of countermeasures or interventions such as caffeine or naps to mitigate or prevent impairments associated with insufficient sleep,” said Namni Goel, PhD, Research Associate Professor of Psychology in Psychiatry at the University of Pennsylvania in Philadelphia.
Namni Goel, PhD
Sleep loss is associated with Alzheimer’s disease and psychiatric disorders and impairs cognitive performance. Deficits in cognitive performance following sleep loss vary between individuals, however. Predicting and detecting individual deficits arising from sleep loss has been difficult.
One set of molecules that regulate gene expression is miRNAs, which are small, noncoding RNAs that typically repress the expression of their target messenger RNAs. Dr. Goel and colleagues investigated whether sleep deprivation or the combination of sleep deprivation and psychologic stress affects miRNA responses in humans. They also examined whether these miRNA responses predict cognitive performance during sleep deprivation.
The investigators enrolled 32 healthy adults (mean age, 35.1; 14 women) in a five-day experiment. Participants underwent two baseline nights with eight hours in bed, followed by 39 hours of TSD and two recovery nights with eight to 10 hours in bed. On the day after TSD, participants underwent a modified Trier Social Stress Test intended to induce psychologic stress. The researchers administered the Psychomotor Vigilance Test (PVT), Digit Symbol Substitution Task (DSST), and Digit Span Task (DS) throughout the experiment. They took blood samples at six time points and analyzed miRNAs in plasma using microarrays.
At the end of the study, levels of 10 miRNAs changed after TSD alone, and levels of 18 miRNAs changed after TSD and psychologic stress, compared with baseline. The former miRNAs target 2,309 genes, and the latter target 2,823 genes. The two groups of miRNAs have 700 targets in common. The researchers also observed that at baseline, 14 miRNAs predicted lapses and errors on PVT during TSD, seven miRNAs predicted DSST performance, and 10 miRNAs predicted DS performance.
“These findings show for the first time that miRNAs can track responses to TSD and its detrimental combination with psychologic stress and predict robust individual differences in various types of cognitive performance,” said Dr. Goel.
—Erik Greb