[Concern] Why do teenagers still suck their fingers when they sleep?

They say that children sucking their fingers when they are young is a normal behavior.

When I was young, I kept sucking my fingers, and no matter what methods I tried, they didn't work.

But now that the children have grown up, they still suck their fingers when they sleep.

Should I also seek psychological counseling in this case??

Is it because I feel anxious or have some psychological issues?

Are there any people around you who have such children?

I'm worried..ㅠ.ㅠ