* Deep sleep
* REM (dream sleep)
Between **3 and 5 a.m.**, many people naturally transition into **lighter sleep stages**, which makes waking up much more likely—especially if stress or noise interrupts the cycle.
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### Cortisol Rhythm
Your body follows a natural hormone rhythm called the **Circadian Rhythm**.
As part of this rhythm, the hormone **Cortisol** begins rising around **3–4 a.m.**. Cortisol helps prepare the body to wake up and become alert.
If stress levels are high, this hormone may rise earlier or faster than normal, which can trigger early awakening.
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### Blood Sugar Regulation
Your body fasts overnight while you sleep. For some people—especially those who eat light dinners or follow low-carbohydrate diets—**blood sugar levels may drop** during the night.
When this happens, the body may release **adrenaline** to stabilize glucose levels, which can cause sudden wakefulness.
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