Here's a concise definition[0]:
"(of a drug) used to enhance memory or other cognitive functions"
There are other definitions. All the ones I've seen have exogenous substances as a common denominator, however.
It's a figurative usage. The OP is not suggesting sleep is literally a nootropic, but that it is something that performs the same function. Like "the best defence is a good offence".
And I don't think it's derailing the topic to talk about relevant alternatives.
The above is a direct quote from OP. Where's the metaphor? You're grossly mistaken!
> but that it is something that performs the same function
Can sleep gives one supranormal cognition? No.
Does sleep perform the same function as modafinil (a drug which gives you more time to work since you need less sleep)? They're nearly opposites.
Does sleep perform the same function as melatonin? A hormone that allows greater sleep "efficiency" than normal sleep. No.
You're grossly incorrect again.
> And I don't think it's derailing the topic to talk about relevant alternatives.
It's a category error.
The sleep conversation is above everything else. It takes focus from the subject at hand.
It happens a lot with noobs. They don't know anything about noots, but know something about sleep/exercise/whatever and decide that's a good topic to talk about.
It's like a conversation about Tesla, and then someone talking about walking—because it's an alternative. OK, the subject may be interesting per se, but it is of little relevance.
Melatonin is the hormone that regulates sleep normally. You're taking additional sleep hormone by taking it orally. So sleep is melatonin.
It's the hormone that is theorized to be involved in the "blue light" sleep effect. When the high-wavelength cones are stimulated, melatonin release is reduced, according to current theory. [0]
"You're taking additional sleep hormone by taking it orally. So sleep is melatonin."
Sleep, and sleep with additional sleep hormone aren't the same thing by definition.
> So sleep is melatonin.
By taking melatonin orally you can get levels which aren't possible endogenously. So melatonin supplements != "vanilla" sleep.
Melatonin is also a mitochondrial anti-oxidant, so may benefit people with "brain fog". Such people may well have to take a supplement to get the maximum benefit. A benefit which can't be reached with natural (what is natural?) sleep.
In older individuals, the endogenous production of melatonin is reduced (happens when people get older). They may also benefit for supplementation. A benefit they couldn't get without it! No matter if they wear blue light blocking glasses, or have f.lux on all their machines.
Sometimes people have to do things at night. Where there's light. It's modern life. They can't go back in time and not be exposed to that light. They may also benefit from supplementation.
One could describe it as enhanced sleep.
I interpret that as I would my example "the best defence is a good offence". It's an out-of-category example given for rhetorical effect.
Perhaps I'm mistaken and that's not what OP meant, but I don't see why you're so certain about it.
>Can sleep gives one supranormal cognition?
Yes if you define "normal" as not getting enough sleep, which is the relevant reference point in this context.
>The sleep conversation is above everything else. It takes focus from the subject at hand.
So collapse that thread and move on. Apparently other people are interested in talking about sleep though.