How Long Should a Power Nap Be? The Science of the 20-Minute NapResearch is clear: 20 minutes is the ideal nap length for alertness without grogginess. Here's the science, plus what a nappuccino is and why it works.Frequently asked questionsIs TimerRush free?Completely free — no account required.Where can I try the timers mentioned in this guide?All timers are at timerrush.com. Bookmark /t/25m or /t/5m for quick one-click access.