20 Minute Timer
Twenty minutes is the number people mean when they say power nap, and the timer above is already set to 20:00. It is also, less romantically, the interval at which you check on almost anything in an oven.
Both uses come down to the same thing: twenty minutes is long enough to matter and short enough that forgetting about it has consequences.
Set Timer
Why the nap number is twenty
Twenty is a practical convention rather than a magic figure. It is the number that keeps a nap short enough to avoid the heavy, disoriented feeling that a long midday sleep often leaves behind, while still allowing five or ten minutes to fall asleep and a genuine stretch of rest after it. Ask around and you will find people who swear by fifteen and people who need thirty; twenty is where most land.
What it is not is a substitute for a short night. A nap tends to patch an afternoon rather than repay what the night owed you, and most people who try to run on that trade notice the difference by the end of the week.
Actually running a twenty-minute nap
Press “Start” before you lie down, not after — fumbling for a laptop once you are settled wakes you up more than the nap will fix. Keep this tab open and the volume up, because a countdown you cannot hear is just a clock. Use the “Test” button on the tone dropdown first if you are not sure the alert will reach you.
When it sounds, sit up straight away rather than negotiating. The lying-there-considering-it phase is where twenty minutes becomes fifty and the evening's bedtime quietly moves.
Twenty minutes in the kitchen
It is the standard first check on roasting vegetables in a hot oven, the point at which you turn a tray of potatoes, and roughly what white rice needs sitting covered off the heat before you touch the lid. Dough resting, a marinade doing its minimum useful work, a joint coming up to room temperature — all twenty-minute jobs.
In every one of those cases the timer is not there because the timing is delicate. It is there because twenty minutes is exactly long enough to start doing something else and forget entirely.