Differentiate between logged in an not logged in users in http header

[tonytony@community.nodebb.org]

I am using Cloudflare to reduce the amount of scraping of my forum. Ideally I would like to make life nicer for logged in users so they are presented with a cloudflare challenge less frequently. The current challenge method causes disconnection notices after a period of inactivity.

Is there an http response header that exists only for logged in users?

P.S. still using version 3.x - no yet made the jump to v4.x