I have experimented with it substantially. I have seen no improvements in my sleep due to phosphatidylserine (PS). My specific sleep issue is one of frequent awakenings throughout the night. I initially thought this was due to cortisol spikes, and thus hoped that PS would come to my aid.
I expect some may benefit from it, but I think it depends quite a bit on the etiology of your sleep difficulties.
Generally, I remain skeptical of how much of an impact PS can have on sleep, as I don’t think its role as a cortisol antagonist has been well described.