There's none or almost no circulation restriction. In fact opposite happens, which results in fluid buildup. Thats why I include a compression sleeve to minimize the fluid buildup over a long period (I'll touch on that little more).
If you are hanging 10lb, then do a 30 minutes sessions. For lighter hanging - 2 1/2 to 5lb - I used it up to 2 hours, but not frequently. Most of the time I hang for about an hour with that weight. For
ADS - I go up to 3 hours.
Its important that you use a compression sleeve when hanging for long a period. The fluid buildup could be minor or major depending on the person. If you are going to hang more than 30 minutes, then use the sleeve. Its better to be safe.
As for the compression sleeve, its very stretchy, but some people have a very large girth, which may cause some circulation loss. For those people, I'm making a larger compression sleeve (lucky bastards). If you have a large girth, email me and I'll send one over when its made.
Again, this is a different kind of hanging and fluid buildup is the enemy, not circulation.