One small 2014 study showed that self-awakening can improve morning alertness and reduce daytime sleepiness. And a small 2005 study shared that self-awakening might be better for your heart. A sudden wake-up call from a blaring alarm clock can raise your blood pressure and speed up your heart rate. It may also increase stress levels and get your morning off to a startling start. Keep in mind, we need more research to show the pros and cons of alarm clocks. And not many of us are able to wake up whenever our bodies are ready — we've got places to be!