Why Does Pain Feel Worse at Night?

Illustration of pain felt at night. (Freepik)

JAKARTA - Not a few people feel that the pain is getting worse at night, even though it can still be tolerated during the day. This condition often makes rest disturbed and sleep quality decreases, especially for those who experience chronic pain.

The phenomenon turns out to have a scientific explanation. Recent research from a team of Chinese scientists revealed a neural mechanism that affects changes in pain intensity throughout the day.

The study, led by Zhang Zhi of the University of Science and Technology of China, was published in the journal Science.

Until now, scientists have known that pain follows a circadian rhythm - that is, it is lighter when the body is active and increases when resting. However, the mechanism behind it has not been fully understood.

The body's internal clock or "biological clock" is located in a part of the brain called the suprachiasmatic nucleus (SCN). This area is known to control sleep cycles and hormones, but its relationship to pain has previously been unclear.

In this study, scientists used virus tracking technology to map the neural pathways between the SCN and the spinal cord in mice. The results showed that the neural activity was influenced by the daily rhythm regulated by the SCN.

Because mice are nocturnal animals, their activity patterns are opposite to humans. When mice rest during the day, the SCN activity increases and strengthens the pain signal in the spinal cord.

Conversely, at night when the mice are active, the SCN activity decreases so that the intensity of the pain signal is reduced.

"This discovery explains why pain sensitivity follows a daily rhythm," said Zhang Zhi.

This finding opens up new opportunities in pain management, especially by adjusting the treatment time based on the body's biological clock so that the results are more optimal.