He was very tight emotionally?

Hi there! I'm not sure I fully understand the word "tight" in the following passage:
[In the funeral of Neil Armstrong's two-year-old daughter,] Grace thought about hugging Neil but stopped herself: "I think he always felt like that wasn't the thing to do. He was very tight emotionally."
--from First Man, by James Hansen

I understand "tight" has many meanings, but I don't know what it means in the sentence above.
Would you please explain or paraphrase it for me?
Thank you!

It means that he was emotionally closed off. He didn't like to show emotions in public (or in general).

tony zhang said:

"He was very tight emotionally."

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This "tight" is the figurative use of literal "The lid of the box was tight. I could not get it off." or "The knot in my shoelaces was tight and I had to cut the laces with scissors." or "The door was tight shut." or "The nut is tight - pass me a spanner."

The idea is that the object that is 'tight' can only be opened/moved/accessed with difficulty (or perhaps not at all).

manfy said:

It means that he was emotionally closed off.

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This seems pretty extreme. I would just conclude that he was reserved or undemonstrative.