The 6 Most Stressful Times of the Day

No surprise that the very thing that jolts you unhappily awake elicits a stress response, driving up your heart rate and blood pressure by two to three points, according to Japanese research. In older people or those prone to heart problems, this sudden jarring can increase heart attack risk.

Your simmer-down plan: If you find that you truly dread your alarm, consider a gradual-awakening alarm, like a wakeup light, which slowly illuminates the room to rouse you. Or use a health tracker like Jawbone Up that nudges you with vibrations when you're in a lighter stage of sleep. (And if you're taking a midday nap and don't have anywhere pressing to be, consider setting no alarm at all. The researchers in the study found that 71 percent of young people and 90 percent of older people can wake themselves up "relatively punctually" after a short snooze—and that's far easier on the heart.)