If you’re often waking around 3 AM each night, it could be your metabolism.
This hour typically coincides with your deepest sleep phase, so consistent early waking suggests something is off.
One common cause is a dip in blood glucose. When levels drop too low overnight, your body releases cortisol, adrenaline, and glucagon to correct it, often jolting you awake in the process. (PMID: 12627733)
This is sometimes referred to as the Somogyi Effect (PMID: 31855369), and it’s especially common in people with poor glycemic control or insulin resistance. So it could be worth trialling a CGM to get a better understanding of your metabolic health.
On the flip side, a different process — the Dawn Phenomenon — involves an early-morning rise in blood glucose triggered by circadian hormone release (PMID: 3510143). Both patterns disrupt sleep, and both are tightly linked to what, when, and how much you eat in the evening.
It can also be other factors. Sleep quality can also suffer from erratic schedules, alcohol, or caffeine after noon.
If 3 AM wakeups are becoming routine, start by finishing your last meal at least three hours before bed and avoid late-night snacks that spike glucose before sleep.
Read more about the Dawn Phenomenon and the Somogyi Effect.
