When you stay in fancy hotel rooms, there’s usually an alarm clock; when you travel cheap and stay in hostels, pensiones, and other low-cost accommodations, you can’t rely on a clock being provided. Or on being able to figure out how to set it and make sure it wakes you up. Having a clock whose workings you’re familiar with can ease a lot of stress.
Get a clock with a built-ion flashlight, or even a really strong glowing face. In many countries, even in better hotels, a midnight trip to the bathroom means a trek down the hall in the dark; use your alarm clock to light your way.