I just finished a bottle of P21 nasal spray and found it very interesting. In fact, if the cost weren't so prohibitive I'd really like to compare it to I.M. cerebrolysin.
One of the most fascinating aspects of P21 was how sometimes it almost felt stimulating, while others it definitely made me sleepy.
All in all, I really do think there were moments of enhanced clarity, calm, and focus I could attribute directly to the nasal spray.
For someone with sleep apnea and idiopathic narcolepsy it almost felt like sleep in a spray...again, at times.
Others, I definitely felt an almost overstimulated fatigue to the point of sleepiness.
I definitely know this feeling. Whenever my body is building something -- musculoskeletal or neurological -- I'll feel that way until I get enough sleep. This effect is most pronounced after bouts of insomnia, when it can help me get the most refreshing naps of my life. I hypothesize a relation to sleep quality due to anecdotal evidence of my phasic insomnia and your apnea & narcolepsy.
Either way, once I've acclimated and/or recovered from low quality of sleep, I find it provides a level of clarity that assists in rapidly absorbing and applying new information. This applies to both mental tasks and visual-spatial-muscular coordination.
I used P21 @1mg daily for 8 weeks (ceretropic spray), I don't think it was even close to all the hype. I'm not sure it did anything for me long-term. That's just me though, lots of people are raving about it.
Is that 500mcg 2x/day? I find that 250mcg - 500mcg 1-2x/day is the sweet spot; any more and I don't get the same incremental effect, so I'd rather subQ. I also usually only use spray occasionally for the short term benefit on top of subQ or days when I'm working away from a desk.
When I use the spray the short term effects are much more pronounced, but I don't get nearly as much of the longer-term effect. My working theory is that subcutaneous administration into adipose tissue acts as a buffering mechanism, delaying the total absorption into the bloodstream and providing a slower, longer exposure to the relevant receptors. Hypothetically, this may help in initiating and reinforcing the neural connections that persist after usage, which would likely result in what we perceive as the long-term effect.
I used it (Ceretropic's) subcutaneously at 500mcg up to 2mg per day with no real effect, injected into very lean areas. More hype than result for me, though others seem to be quite fond of it.
When I subq, I usually do 500mcg - 1mg twice per day, occasionally adding the nasal spray in between or in the evening. I also find the longer-term effects only appear after a few days that include practice in whatever area I'm trying to improve. It can increase my ability to train and retain new patterns in short bursts, but if I don't get the right diet and sleep some of that benefit is lost. It seems to provide a mild short-term acuity with a subtler improvement in time between learning and retention when added to a training, studying, and working regimen that already produces results.
My regimen:
subQ: 750mcg - 1mg (twice a day on active days, once a day when not, taking a few days off per week)
I have had a noticeable increase in efficiency and clarity of work output in the past week since starting a p21 regimen again. Initially, I slept like a baby, then it began to deliver the results I expected. The sensation of calm awareness can become sleepiness if I haven't been getting enough quality sleep.
nasal spray: 500mcg (as needed)
Occasionally, I will prepare my own nasal spray with 250mcg, 500mcg, or 1mg for shorter term use when I'm out or want a shorter duration of effect. I feel like the sweet spot is around 500mcg in nasal spray -- any more doesn't significantly enhance the short term effect, and would be much more effective subq.
The ROA does affect my subjective experience. I find nasal provides a more noticeable immediate psychological effect, but it does not persist and provide the same level of longer term effects that subQ does. It makes perfect sense, since intranasal adminstration would provide direct access to the bloodstream near the brain as well as a certain amount of inefficiency. subq/IM/IV should provide the highest possible bioavailability, but subq into fatty tissue should serve to buffer the compound's introduction into the bloodstream.