I got the glasses because I hoped they would help my sleep--I'm not sure I would say I believed they would.
I totally agree that it may be the placebo effect. However, I feel that it's important to note in discussions of the placebo effect that it's fairly irrelevant whether an intervention works because of the placebo effect or some other reason--what matters is whether the intervention works. And this one does, at least for me.
If an intervention only 'works' because of the placebo effect, than that intervention doesn't actually work and there is no reason for someone else to use it. If my sleep is improved by listening to death metal with the volume set to high, then good for me and I can continue doing it, but you probably shouldn't copy me, and may explain to people that they probably shouldn't buy my 10$ death metal sleeping app.
Note: I'm not accusing you of trying to sell something, I hope my comment doesn't come up that way.
On the contrary: if it works it works. Just because it's a placebo doesn't mean it only works for one person. The only reason we know that the placebo effect exists because we can show in multiple studies that certain placebos work on a lot of people. In fact, some placebos work better than other placebos[1].
Of course, there are pitfalls. It's important that doctors not lie to their patients, because patients need to trust their doctors, and patients need to be able to make informed choices. And as you pointed out, it's obviously wrong to sell a placebo as if it were not a placebo. But even this doesn't mean placebos are useless: some placebos work even when you know they are placebos[2].
There are many cases where placebo performs better than nothing, and it would be foolish to not use this effect to improve our lives.
From what I've read, the placebo effect is still mysterious, and the only place where it is consistently found to help is in pain perception. Outside of this, there are some studies which show improvements in placebo when compared to no treatment, but other studies ([1][2][3]) find no improvement or only perceived improvement - e.g. the patient feels that they slept better, but in fact they slept the same amount and it took them just as long to get to sleep.
So, overall, it's not clear whether the placebo effect is a real effect that placebos have on patient health, or whether it is an artifact in the data, e.g. due to reporting errors, especially in studies which are not double blind (where the researcher may be biased themselves in the way they are collecting the data). There are also many studies which compare an active substance to a placebo treatment but have no data about patient response under no treatment, which is itself not necessarily 0 [2].
Edit: added a [3] that is explicitly about insomnia - placebo was found to improve subjective perception of sleep quality, but not objective measures (sleep onset latency).
That's interesting, and it's good to know that my sleep improvement might be perceived rather than actual.
That said, this is just evidence that the placebo effect may not apply in this case. It's not evidence that if interventions only work due to the placebo effect, they don't work. You've convinced me that I'm probably not experiencing benefits from the placebo effect in this case, but that conclusion is unrelated to the conclusion of your previous post.
I'll also add that your assertion that pain perception is the only thing that responds to placebo is incorrect. Placebo is effective on a wide variety of things, including weight loss[1], itching[2], asthma[3] and warts[4] (that last one surprised me).
There's also lots of cases where placebo makes things worse, such as people responding to placebo poison ivy[5].
Finally, there's lots of cases where things which were used in studies for placebos turn out to be active. For example, a study of insulin and chromium in sugary foods for diabetics used apple pie as a control source of sugar, but discovered that the cinnamon in the pie produced a larger effect on insulin resistance than the chromium.
I'll add a bit to @kerkeslager response in stating that a placebo is something that works because you are told it will work. Your example of death metal would only be a placebo affect if someone told you that listening to death metal will help your sleep and then it did. If you are just a hard core rocker and got used to listening to death metal to sleep and now you find that without it you don't sleep as well, that isn't the same thing as a placebo affect.
But I am interested in what a death metal sleeping app would actually look like. Of course I would have to ask if it's needed in the market place (does it create value), as opposed to just playing my Demented Ted playlist.
> I'll add a bit to @kerkeslager response in stating that a placebo is something that works because you are told it will work
Yes, that was part of my initial point - to the extent that placebo exists, anything can be turned into a placebo with enough marketing. Avoiding blue light could help with sleep quality. Adding more blue light could help with sleep quality. Faith healing could help with sleep quality. Homeopathy, traditional Chinese medicine, ayurvedic medicine, leeching, blood-letting etc. If it only depends on you believing in it, but it does help, I would recommend the cheapest possible remedy that you can bring yourself to trust, and that doesn't have a proven anti-effect (coffee therapy for curing insomnia may not be an effective treatment).
I also detailed some skepticism of the placebo effect in another response here.
> If an intervention only 'works' because of the placebo effect, than that intervention doesn't actually work and there is no reason for someone else to use it.
Absence of proof doesn't mean proof of absence. So it may or may not be placebo, but it's an interesting data point for me (just bought blue blocker glasses, plan to try out. At $15-20 per, it's a no-brainer even if it doesn't work out).
I agree that they do seem like a no brainer, I don't have them for sleep but I did buy a pair of the glasses for looking at computer screens, and they do seem to help when I'm spending too much time in Word and Excel.
I totally agree that it may be the placebo effect. However, I feel that it's important to note in discussions of the placebo effect that it's fairly irrelevant whether an intervention works because of the placebo effect or some other reason--what matters is whether the intervention works. And this one does, at least for me.