2. Shifts in the internal clock (circadian rhythm)

Another common cause is a shift in the body’s internal timing system.

Many older adults feel sleepy earlier in the evening. If someone goes to bed at 9:00 p.m., their body may naturally complete its sleep cycle around 3:00 or 4:00 a.m.

This isn’t always insomnia — sometimes it’s simply a new rhythm.

The shift can become more noticeable when:

• A person retires
• Social interaction decreases
• Daily responsibilities lessen
• Evenings become quieter
• Without strong external cues, the body relies more heavily on its internal clock.

3. Physical discomfort and health factors

The body may also wake up in response to mild physical discomfort that isn’t obvious during the day.