By Christine Spines
Updated May 01, 2009 at 12:00 PM EDT

Jay Leno was hospitalized and missed two tapings of The Tonight Show last week because of “exhaustion.” The cause of the late night host’s sudden illness remained a mystery until he told he had gotten “worn out” from the rigorous schedule of his nightly talk show in addition to writing columns for various car-related publications and doing standup comedy performances.