Apple Clock

While hitting snooze won't help you much if you fall back asleep, it can help you wake up more gently. However, your iPhone's default nine-minute snooze may be too long or too short for your preferences. If you tend to fall back asleep quickly, you might be better with a two-minute snooze.

The native timer feature on your iPhone works well enough that you probably haven't even thought about installing a third-party timer. With just a few taps, you can get a countdown for any amount of time up to 24 hours (or one second shy of 24 hours, to be precise). But as fast as it can be to set a timer from the Clock app, there are even faster ways to start the countdown.