Sleep science describes insomnia with three P's:
Predisposition. Some of us run a little more wired — lighter sleepers, busier minds, more sensitive stress systems. A starting point, not a sentence; plenty of predisposed people sleep fine their whole lives.
Precipitant. The thing that tipped you over: a stressful season, an illness, grief, a schedule upheaval. Bad nights in hard times are completely normal, and for most people sleep returns when the storm passes.
Perpetuation. Sometimes it doesn't return — because during the bad nights, you started doing sensible things:
Remember the machinery. Extra time in bed dilutes your sleep pressure across more hours. Lie-ins and naps drain the tank and shift the clock. So the next night is worse — and you cope harder. That's the loop.
And a second loop runs on top: the mental one. Enough bad nights and the bed itself starts to mean frustration. You're sleepy on the couch at ten — and wide awake the moment your head hits the pillow. Your body learned that lying down is when the struggle starts.
You can't change your predisposition, and the precipitant already happened. But the perpetuating loop — the behaviors and learned associations — is running right now, which means it can be interrupted right now. That's the part CBT-I attacks. And it's the part keeping you up.
This week your only job is evidence: five diary mornings, and we can see your personal loop in numbers. Next week, we start cutting.