Why doesn't Px cause insomnia?Updated 7 days ago

The main reason Px is afternoon- and sleep-friendly is because of the significantly shorter half-life. Caffeine's half-life (time it takes for concentration to cut in half in your body) is about 5-6 hours, whereas Px is about 4-5 hours. After caffeine gets metabolized into its metabolites (theobromine, theophylline, and paraxanthine (Px)), those then need to be metabolized, which also takes additional time. 

This means that it takes nearly all day to get caffeine out of your system, whereas it takes much less time for Px to be processed by your body, leaving you free to rest soundly.