A new study indicates that “if you’re in the mindset that you’re well-rested, your brain will perform better, regardless of the actual quality of your sleep”:
Participating undergrads first reported how deeply they’d slept the night before, on a scale of one to 10. The researchers then gave the participants a quick, five-minute lesson about sleep’s effect on cognitive function, telling them it was just background information for the study. … Then participants were hooked up to equipment that they were told would read their pulse, heartrate, and brainwave frequency, though it actually just measured their brainwave frequency. They were told that these measurements would allow the researchers to tell how much REM sleep they’d gotten the night before. This was not true. …
Participants who were told they had above-average REM sleep performed better on the test, and those who were told their REM sleep was below average performed worse, even when researchers controlled for the subjects’ self-reported sleep quality.
The Dish 