The only thing I've found effective is modafinil for alertness and some general mental sharpness. Especially after a night of poor sleep, the mental alertness it provides is a god-send.
Modafinil has a long half-life of 13-15 hours, which means that if you take a dose at 9AM, half of it is still in your bloodstream at midnight. This can have a negative effect on sleep quality the following night, which tends to prompt users to want to take yet another dose the following morning, and so on.
Modafinil is also notorious for reducing verbal fluency in some (though not all) users. There are also plenty of reports of abused and dependence online, though not to the same degree as other stimulants. From what I can gather, most people who use it regularly for non-prescription purposes eventually give up due to escalating tolerance.
Most other nootropics compounds follow similar stories: Initial glorification, widespread uptake, steady loss of momentum as people realize the compound is not without tradeoffs and downsides, and eventually being relegated to an every once-in-a-while tool for those who have it.
In some cases, the negative side effects of a substance are so subtle that people don't make the connection at first. For example, cholinergic supplements are frequently touted as memory enhancers and miracle supplements. Unfortunately, cholinergic supplements also have a tendency to induce or worsen depressive symptoms over time. The Nootropics communities are full of people complaining about unexplained depressive symptoms while taking various choline supplements that they hoped would improve their cognition or memory.
It's interesting to watch from the sidelines, but at this point I've decided that nothing beats good sleep, exercise, social exposure, and good diet. Caffeine is an okay band-aid on difficult days when used in moderation, but any attempts to use powerful compounds to override sleepiness seem doomed to backfire with rebound effects later.
I have never tried modafinil (or any other nootropics) - will read more about it. However, based on my very brief review, it appears to be much less safe than Nootropil along with a questionable effectiveness as a "cognitive enhancer". Plus, unlike Nootropil, it is considered a controlled substance in the United States.
I also take 2g of magnesium l-threonate per day. As a stimulant I take phenylpiracetam at 100mg per dose on a per need basis. Semax and selank I take on occasion.
Ice baths have also been very helpful. I'll leave it at that; pm me for further info.
Ice baths: that's for mental acuity, or overall physical health? I know it's used frequently in high-level sports for recuperation purposes.
It's for the mental acuity, but I'm happy for any benefits I can get, such as a higher white blood cell count and more brown adipose tissue, the loss of which is associated with aging.
Strangely enough, one thing that I find is also helping is a balaclava. I'm standing here like an idiot with a balaclava on because I find it helps me stay focused. I got it a few days ago to use when hiking. I just happened to notice while trying it on that I felt a little calmer. I used it last night while working and finally managed to get some shit done.
I'm also using spaced repetition to try to remember things. No apps or programs yet, just manual note taking and repetition.
Also, the balaclava is interesting: I can imagine the benefit is almost similar to that people get from using a gravity blanket. The weight and "hugging" effect might be very comforting.
Really sorry to hear about the sleep apnea; that's an awful problem to deal with. Hope you're able to find a treatment which works for you.
It takes 4-8 weeks to kick in and the two most common side effects people complain about are stomach issues and lack of motivation.
For me it's a good night's sleep. I need 8 to 10 hours for best effects. Complemented by a 20-30 min. siesta after lunch, when possible, particularly in the summer. The feeling of being fresh and sharp in the morning is almost physical.