What to do at 3 a.m.

Waking briefly at night gets more common with every decade — that part is normal physiology, not a malfunction. The problem isn’t the wake-up. It’s the 40 minutes of ceiling negotiation that follows.

Sleep researchers have a rule for this that’s almost insultingly simple: if you’ve been awake more than about 20 minutes, get out of bed. Sit somewhere dim. Do something genuinely boring — paper book, not phone. Go back when your eyelids get heavy, not when you decide it’s time.

Why it works: beds are associative. Every hour spent frustrated in bed teaches your brain that bed is where the arguing happens. Every return-when-sleepy teaches it the opposite.

Today’s move: decide your 3 a.m. plan now, while it’s daytime and you’re reasonable. Pick the chair. Pick the boring book. At 3 a.m. you don’t want decisions — you want a script.

— Sam