The external jugular vein is often not exposed when a normal person stands or lies down, but it may be slightly filled when lying down. If it is obviously full when sitting or semi-sitting, it is an abnormal sign, suggesting that jugular vein pressure is elevated, which can be seen in heart failure, constrictive pericarditis and so on.

Of course, this only applies to most people.

There should be nothing wrong with the heart at such a young age.

Go to the hospital for a check-up if you don't feel at ease.