Waking up is one of the leading ways to end a period spent asleep, and overall it's probably the one that least limits one's future actions. But there is the problem of how to get up. Due to the increased crowding of cities in the 18th and 19th centuries the meal which had formerly been ``dinner'', an early afternoon repast for which people went home, split into the lunch and dinner (or in some areas, dinner and supper, and in some other areas, Food Consumption Period Two and Burgers), with the first moving closer to noon and the second closer to about sixish. Lunch, or supper, then repeatedly shoved breakfast until it went running to sometime before 9 am, from which it was relatively safe. But this meant people who ate breakfast -- and, going by its literal meaning, everyone had to -- now had to get up earlier, or face the risks of eating while asleep, such as buttering a day calendar or suffering the heartbreak of oatmeal pillow.
The problem is hours like this are generally too early to wake up by a natural process of running completely out of fatigue and rolling off the bed. The easiest way to sleep until you're no longer tired and then get up well before 9 am is to simply sleep in, and then dial your clock backwards the appropriate number of hours. For example, if you wake and find that it's 10:30 am, and you want to be awake before eight, then you need to wind the clock backwards by seven hours. This is because you always overdo it, a common flaw of enthusiastic youth. That problem can be solved by becoming grumpy. Unfortunately while the technique is fine in isolation, it fails to work in larger groups, as people need different numbers of extra hours to wind back. You could go around to all the people you expect to interact with during the day and turn their clocks back by the same amount, but you have to wake up before you do that anyway, and besides they'd be sneaking into your place to turn your clock back to match theirs. Plus there's always someone who thinks that it would just be keen if everybody got up early and got into work bright-eyed and bushy-tailed, up until they got sued for trademark infringement by squirrels. Negotiations to settle out-of-court were going well, until 7:45 am, when they were pulled away by an Eastern Gray and buried under an oak tree for the winter. So you can go around changing clocks as you like at least until the germinating season (and again a few months later when the germinating season takes nearly a week off for the all-star game). But we need a more reliable solution.
Alarm clocks have always been popular ways to make one get up when one doesn't want to: these simple devices, set to an appropriate time, will disrupt your sleep by reminding you about how much you have in savings or by pointing out that you don't actually know where your medical insurance card is, and they might disturb you enough to get you fully awake. But to function they need to keep finding new things that you worry yourself awake about, so that even the best alarm clocks lose their effectiveness in time. If you happen to have your body replaced with a steampunk mechanical design then a clock can be very easily added adorably cutely in your belly, and then it can simply ring, causing your entire body to vibrate until you awaken. Unfortunately this action may cause vitally needed screws to fall out, so it would be wise to tape yourself down before the alarm goes off. Finding people to tape you can be an exciting way of breaking the ice with your neighbors. Ask politely. If you're shy, ask while they're still asleep.
Trivia: In 1844 Charles Babbage invented a mechanical time-card clock. Source: Time's Pendulum: The Quest to Capture Time -- From Sundials to Atomic Clocks, Jo Ellen Barnett.
Currently Reading: 1776, David McCullough.