the.com/drowsiness
the brain dimming the lights before it kicks you out of consciousness entirely
chemical culpritAdenosine builds all day, then knocks you out
caffeine trickCoffee blocks adenosine, doesn't remove it
warm warningDriving while drowsy rivals drunk driving danger
microsleepsBrain can nap for seconds, eyes open
post-lunch dipAfternoon slump is a real circadian event