Now this is an alarm clock for the heaviest sleeper. If you're the type who sleeps through anything — thunderstorms, loud neighbors, earthquakes, the zombie apocalypse — you've finally met your match. Sonic Alert's Sonic Bomb Alarm Clock doesn't just rely on its 113-decibel alarm to pry your eyelids open (for comparison, that's about the same decibel level as a car horn or snow blower going off in your ear), it also has a shaker device that slips underneath your mattress or pillow to jiggle you awake, and red flashing lights that trigger with the alarm.
The most accurate mechanical timekeeper is the Shortt pendulum clock; it makes use of the movement described above for electric master clock systems. The Shortt pendulum clock consists of two separate clocks, one of which synchronizes the other. The timekeeping element is a pendulum that swings freely, except that once every half minute it receives an impulse from a gently falling lever. This lever is released by an electrical signal transmitted from its slave clock. After the impulse has been sent, a synchronizing signal is transmitted back to the slave clock that ensures that the impulse to the free pendulum will be released exactly a half minute later than the previous impulse. The pendulum swings in a sealed box in which the air is kept at a constant, low pressure. Shortt clocks in observatories are kept in a room, usually a basement, where the temperature remains nearly constant, and under these conditions they can maintain the correct time to within a few thousandths of a second per day.
Greek astronomer Andronicus of Cyrrhus supervised the construction of the Tower of the Winds in Athens in the 1st century B.C. The Greek and Roman civilizations are credited for initially advancing water clock design to include complex gearing, which was connected to fanciful automata and also resulted in improved accuracy. These advances were passed on through Byzantium and Islamic times, eventually making their way back to Europe. Independently, the Chinese developed their own advanced water clocks（水鐘）in 725 A.D., passing their ideas on to Korea and Japan.
Here at the Strategist, we like to think of ourselves as crazy (in the good way) about the stuff we buy (like pillows), but as much as we’d like to, we can’t try everything. Which is why we have People’s Choice, in which we find the best-reviewed (that’s four-to-five-star reviews and lots of ‘em) products and single out the most convincing. While we’ve tried to find the nicest-sounding alarm clocks and ended up with picks for the best alarm clock and a voice-controlled alarm clock, we wanted to see what other ways to wake up were out there. So we found the best alarm clocks on Amazon, according to hyperenthusiastic reviewers. (Note that reviews have been edited for length and clarity.)