Huddle together/huddle up

Hello,

Do both of the sentences below sound natural?

- There was no heating in the room, so we huddled together for warmth.

- There was no heating in the room, so we huddled up for warmth.

Both of them sound okay to me, but I seem to have a slight preference for "huddle up", I don't know why. Together might be the more logical choice, as "huddle up" can be used in other contexts.

Thank you.