Waking up in the middle of the night—especially between 3 and 5 a.m.—is more common than you think. And while it might feel random, it’s rarely “just insomnia.” This quiet window, sometimes called “the hour of the wolf” (a term from Scandinavian folklore for the time when anxiety peaks and spirits roam), actually aligns with natural rhythms in your body and mind.
Here’s what science and sleep experts say about why this happens—and what you can do about it.
🌙 1. Your Circadian Rhythm & Sleep Cycles
- Adults cycle through 4–6 sleep cycles per night, each lasting about 90 minutes.
- By 3–5 a.m., you’re typically in your lightest sleep phase (REM or Stage 1), making you more prone to waking from small disturbances (noise, temperature, stress hormones).
- If you go to bed around 10–11 p.m., this window often coincides with the end of your 4th or 5th cycle—a natural transition point.
✅ Normal? Yes—brief awakenings are part of healthy sleep. The issue is not being able to fall back asleep.
🧠 2. Cortisol & Stress Hormone Surge
