You were fine all day. You go to bed. And suddenly, your tooth is unbearable.
You’re not imagining it. Here’s what’s actually happening 
Gravity is no longer helping you
When you’re upright, blood flows downward, away from your head. The moment you lie down, blood pressure increases in your head and face, including around an already inflamed tooth. More pressure = more pain.
Your brain has nothing else to focus on
During the day, distractions dampen pain perception. At night, silence removes every competing signal. Your nervous system has one job now and it’s feeling that tooth.
Your natural painkillers drop
Cortisol! Your body’s built-in anti-inflammatory peaks in the morning and drops at night. Less cortisol at bedtime means inflammation is less suppressed. Dental pain takes full advantage.
It usually means something is already wrong
In my clinical experience, patients who describe unbearable nocturnal toothache almost always have underlying periapical pathology: infection at the root tip that’s been quietly developing. This is the tooth telling you it has reached a point where it cannot wait.
I’ve seen this pattern repeatedly in patients who “managed” mild discomfort for weeks finally turning up at the clinic after a sleepless night. My own mother went through exactly this.
The pain at night isn’t new pain. It’s the same problem your body was politely hiding during daylight hours.
If your tooth is waking you up at night, don’t wait for morning to book that appointment.
Have you ever had a toothache that only hit you at night? What did it turn out to be?
MBH/DB