The best nootropic is getting a good nights sleep. It takes effort! Preparing for bed early and disciplining yourself to put the light out is not easy. Not nearly as easy as popping a pill. But it's so much more effective than any drug listed here. And for a safe and provable quick cognitive boost, take some caffeine, preferable green tea with theanine.
It's hard for me to fall asleep. I haven't cracked it yet how to do it perfectly. What helps: view the problem as improving your likelihood to sleep. Before I viewed the problem as falling asleep 100% of the time, which is a really defeating view to have when I can't fall asleep. Sleep tips that help me: 1. meditation: still experimenting with body-scan vs. breath meditation, they both help but have different effects…
Also can attest through personal experience that the caffeine + power nap works wonders (I usually use my espresso machine)