If blood sugar drops:

The liver releases glucose,
and the body secretes cortisol and adrenaline,
two hormones… which naturally promote wakefulness.

The result: a sudden awakening, sometimes accompanied by a feeling of tension or increased alertness.

Late meals, dinners too high in carbohydrates, or alcohol consumption can accentuate this mechanism.

The sleep environment: a detail that changes everything
Is the room cool, dark, and quiet?
It seems obvious, but these conditions remain essential.

Between 3 a.m. and 4 a.m., the brain becomes more reactive to external stimuli. Thus, a:

Heating too high.
draft,
snoring,
car passing
or even a street light
may cause an awakening.

At this time of night, even the micro-movements of the partner have a greater impact.