The placebo effect is any outcome that is not attributed to a specific treatment but rather to an individual's mindset (Benson & Friedman, 1996). This phenomenon can extend beyond its typical use in pharmaceutical drugs to involve aspects of everyday life, such as the effect of sleep on cognitive functioning. In 2 studies examining whether perceived sleep quality affects cognitive functioning, 164 participants reported their previous night's sleep quality. They were then randomly assigned to 1 of 2 sleep quality conditions or 2 control conditions. Those in the "above average" sleep quality condition were informed that they had spent 28.7% of their total sleep time in REM, whereas those in the "below average" sleep quality condition were informed that they had only spent 16.2% of their time in REM sleep. Assigned sleep quality but not self-reported sleep quality significantly predicted participants' scores on the Paced Auditory Serial Addition Test and Controlled Oral Word Association Task. Assigned sleep quality did not predict participants' scores on the Digit Span task, as expected, nor did it predict scores on the Symbol Digit Modalities Test, which was unexpected. The control conditions showed that the findings were not due to demand characteristics from the experimental protocol. These findings supported the hypothesis that mindset can influence cognitive states in both positive and negative directions, suggesting a means of controlling one's health and cognition. (PsycINFO Database Record (c) 2014 APA, all rights reserved).
Actually, this just shows that believing you will perform better improves performance. They weren't just told they'd slept better, they were also told that sleeping better improves performance:
>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.
Yeah; it could very well have been the case that had the researchers given a quick, five-minute lesson about how "short bouts of sleep deprivation improve cognitive function ...because SCIENCE [wave hands frantically]" that they could have shown the opposite result as well ;P.
It's all related to placebo effect and positive attitude - perhaps throwing in the concept of hope. You could throw the idea of intent in there as well. Basically along the lines of once you initiate positives-feel-good thoughts then those will impact everything else you do - and things like exercise that increase good feelings physically, then those associated thoughts and memories will have more feel-good attached to them. Bit of a tangent I went on..
Nobody mentioned anxiety? Everyone's heard of all kinds of stupid accidents, well, I'd never do something that dumb. Well, after being awake 24 hours either you understand it could happen, or you're not very self aware. Being told you've got plenty of sleep and should be able to do the job just fine reduces anxiety and the lack of anxiety improves performance.
I own a table saw and still have all my fingers. I know all about doing dangerous stuff while well rested, sober, calm. As an example, had a board kickback on Friday evening, I know what I'm doing and work safely so I know nothing will happen when it kicks back so I can focus 100% on other things, like keeping my fingers well away from the blade. If I was all anxious in general or about kickbacks I'd probably end up sticking a finger in the blade, or I'd work at about 1/10th speed just to make sure.
I have been on Ambien (Zolpidem here in the UK) for 5 years now after being diagnosed with insomnia due to PTSD (actually diagnosed by three doctors at a psychiatric hospital where I had to spend 4 months in 2009 not some self-diagnosis) and I am not too sure on this evidence. I know a lot of people who suffer true insomnia (as in doing several days with perhaps 15 minutes sleep) and thinking you got good sleep does not make up for the fact that you are actually going several days with awful sleep. I am sure there is some kind of psychosomatic side that makes you perform better because you think you will but suffering real lack of sleep cannot be "tricked" better with positive thinking just like how depression cannot be fixed by just "thinking happy".
The study population was undergrad students, not insomniacs (I mean, maybe self-styled, but you know what I mean). Therefore, you're probably right that this finding might not generalize to a distinct population with disordered sleep. But for the typical HN reader, it might be of more interest.
I found out that under-sleeping had a very bad impact on me after several months, not in a short/mid term. And I have the feeling this placebo effect would not be the same if you've been under-sleeping for months.
The original article link is broken though, too bad.
This is just my gut feeling, things are probably more complex, but here's why I think sleep deprivation deeply impacts us:
I used to have a crazy schedule, commuting very early and coming back quite late at home, sleeping between 4 to 5 hours a day. I've noticed
I was often in a bad mood, dropping things, feeling anxious. gaining weight and so on... After a couple of years I was feeling depressed and getting sick all the time.
Then I had a new job and started to work remotely from home, and started to sleep 8 to 9 hours per night. Both works were interesting, and commuting to the first one was done by train, so I think the only noticeable difference was the amount of sleep I was getting.
With more sleep, after a month, I became more focused in everything, the depression feelings went away, and had so much more energy. Overall I was more successful in what I was doing - happier and healthier.
I guess all of this sounds obvious, but going through it, making sure I get my 8-9 hours of sleep most of the time is something I am now careful about.
Speaking for myself; believing I slept too short/badly (like when I think I lay awake most of the night while my wife saw I slept solidly) impairs my performance worse than believing I slept well while I haven't improves it.
Very true. I noticed that if I stop looking at the clock before I go to sleep and I assume I'm getting 8 hours of sleep I wake up feeling great. A few times I glanced at the time when setting my alarm and just knowing how many hours I'm going to get makes me wake up tired. So I went around the house and put tape over the clocks I couldn't turn off (microwave). Turns out life without knowing the time is a lot more calm, productive, and enjoyable.
Paywalled article: http://psycnet.apa.org/doi/10.1037/a0035546
Abstract:
The placebo effect is any outcome that is not attributed to a specific treatment but rather to an individual's mindset (Benson & Friedman, 1996). This phenomenon can extend beyond its typical use in pharmaceutical drugs to involve aspects of everyday life, such as the effect of sleep on cognitive functioning. In 2 studies examining whether perceived sleep quality affects cognitive functioning, 164 participants reported their previous night's sleep quality. They were then randomly assigned to 1 of 2 sleep quality conditions or 2 control conditions. Those in the "above average" sleep quality condition were informed that they had spent 28.7% of their total sleep time in REM, whereas those in the "below average" sleep quality condition were informed that they had only spent 16.2% of their time in REM sleep. Assigned sleep quality but not self-reported sleep quality significantly predicted participants' scores on the Paced Auditory Serial Addition Test and Controlled Oral Word Association Task. Assigned sleep quality did not predict participants' scores on the Digit Span task, as expected, nor did it predict scores on the Symbol Digit Modalities Test, which was unexpected. The control conditions showed that the findings were not due to demand characteristics from the experimental protocol. These findings supported the hypothesis that mindset can influence cognitive states in both positive and negative directions, suggesting a means of controlling one's health and cognition. (PsycINFO Database Record (c) 2014 APA, all rights reserved).