Can Lying to Yourself About How You Slept Actually Make You Smarter (or Dumber)?

You wake up. Your head feels a little heavy, and your sleep felt merely mediocre. You sit down at the computer, open some attention and thinking-speed tests, and suddenly notice your brain is working worse than usual. It seems logical: slept poorly → thinking poorly. But what if the entire difference isn’t in the actual sleep you got, but in what someone told you about it?

That is exactly what Christine Draganich and Kimberly Erdal tested in 2014 at Colorado College. They ran an experiment that feels almost like scientific trolling, yet revealed profound truths about the human mind.

It all started innocently enough. Students were brought into a sleep lab, hooked up to a bunch of sensors (looking exactly like a real polysomnography setup), and allowed to sleep through the night. In the morning, each participant was told: "We’ve analyzed your sleep patterns. Here are the results."

And that is where the magic began.

The Experiment: A Tale of Two Groups

In reality, nothing was measured. All the numbers were completely made up, and the REM percentages were assigned randomly. The actual quality of sleep was roughly the same across both groups. However, the feedback they received was drastically different:

• The "Above Average" Group: They were told, "You spent 28.7% of your night in REM sleep — that’s significantly above average. You should feel sharp and cognitively on point today."
• The "Below Average" Group: They heard, "You only had 16.2% REM — that’s below average. Your concentration and reaction speed will probably be reduced today."

So what happened?

The results were stunning. The people who were told they had "great sleep" actually performed significantly better on tests of attention and verbal fluency:

1. The Paced Auditory Serial Addition Test (PASAT): A difficult task where numbers are read quickly, and you must keep adding the newest one to the previous one in your head.
2. The Controlled Oral Word Association Task (COWAT): A verbal fluency test where you must name as many words starting with a specific letter (like "F") as you can in one minute.

Conversely, the students who were told "you slept badly" genuinely scored worse — even though everyone had slept about the same amount and quality! This is a classic placebo effect, except it wasn’t applied to pills or medical treatment — it was applied to your own mind. More precisely: placebo sleep.

Why does this even work?

Your brain absolutely hates uncertainty. When you wake up not knowing for sure whether you slept well or not, it looks for clues. If an authoritative person (preferably wearing a lab coat and showing fancy graphs) tells you, "You slept like a champion," your brain effectively says: "Cool, full power mode activated."

Hypothetically, this expectation triggers a physiological cascade: it can lower cortisol (stress hormone), raise dopamine, and improve blood flow to the prefrontal cortex — the area responsible for executive function. You actually become a bit smarter for a while.

The reverse is also true (the nocebo effect). Tell someone "you slept like garbage," and the brain switches to energy-saving mode: attention scatters, processing speed drops, and mistakes increase. It is not faking it — these are real physiological changes driven by belief.

This isn’t the only example

The placebo effect on cognitive performance has been studied many times, proving that our expectations shape our reality:

• Caffeine Expectancy: People who are told they are drinking real caffeinated coffee (but are actually drinking decaf) show better attention and faster reactions than those who know they are drinking decaf.
• Genetic Priming: Students who are told before an exam, "This test shows you are genetically predisposed to high intelligence," actually score higher — even when no genetic test ever happened.
• The Milkshake Study: In a famous 2011 study, Alia Crum gave people milkshakes. One group was told it was a 620-calorie indulgent shake, the other that it was a low-cal 140-calorie "sensible" version. The people who believed they drank the indulgent one had a significantly larger drop in ghrelin (the hunger hormone). Their bodies genuinely acted as if they were fuller.

So we are not just "tricking ourselves." We are physiologically reprogramming the body through expectations.

What does this mean for everyday life?

How you explain your own state to yourself matters more than the state itself.

Woke up groggy? Instead of thinking, "Ugh, I slept terribly, the day is ruined," try telling yourself: "The night was short, but my REM was solid — I will be firing on all cylinders soon." It sounds ridiculous, but the neuroscience suggests it works.

Other people can control your performance with a single sentence.

If someone says first thing in the morning, "You look tired today," there is a real chance you will start dragging. Conversely, hearing "You look refreshed!" can give you an actual energy boost. Self-talk isn’t woo-woo — it is applied neuroscience. The same mechanisms that make placebo pills reduce pain can make you more focused, creative, or quick-witted — simply because you believed the story.

So the next time