History tells us (but only over a quiet candlelit dinner) that the primitive man would often have trouble getting out of the cave early enough for the hunt. Rather than rely on natural stimulants such as daybreak or the consumption of a limb by a predator, he would ask a more reliable cavemate to guide him from slumber. Cave drawings show that the first human to serve this role, named Noodge, pioneered a very effective technique that only distant descendants would appreciate as an advanced application of physics. As far as the silly caveman knew, he was simply being hit in the head with a rock.
Fast-forward a few hundred thousand years to when science brought us the alarm clock. While much more sophisticated than the rock of ancient times, it did not prove significantly more effective at waking consumers at first. The product was nearly deemed a failure until someone took the cord used to sling it at the sleeping party and plugged the device into a wall. Consumers rejoiced in the new freedom from concussions, oblivious that they had set in motion a turn of events that would ultimately lead to the much more painful morning radio "zoo" show.
Since its early days, the alarm clock has seen many changes. It made the transition to digital display. It incorporated the cassette, the CD, and even in some instances, the cordless phone. Many models now offers such functionality as automatic time setting, dual alarms, countdown timers, battery backup and snooze (a real sleeper feature). An alarm clock feature is conveniently built into many cell phones these days. You can't miss it - fourth deck down, eighth menu item.