Anatomy of an All-Nighter

Happy midterms! Here’s the Anatomy of an All-Nighter from the University of Texas at Austin.

4:00-5:00 a.m.

Second wind. As the circadian cycle moves toward morning and the alert phase, body temperature rises. Even the person who hasn’t slept a wink begins to feel a second wind. Pseudo-second winds can be brought on throughout the night by stimulants like exercise, caffeine, protein, conversation, or cold air.

Catnap caution. The desire to NOD OFF is strongest now, since the biological clock is ticking its slowest. It’s a good time to nap because the circadian rhythm is shifting into higher gear, making it easier to rise after one or two hours of rest. But shorter naps may do more harm than good. When tired people doze off, they immediately enter the deepest stage of sleep. If they get up after 15 minutes, they may not feel alert for another hour — a phenomenon called SLEEP INERTIA.