Richard Simmons -- Hospitalized For 'Bizarre Behavior'

Richard Simmons was taken to a Los Angeles hospital late Friday night after exhibiting bizarre conduct ... TMZ has learned.

Sources tell us, Simmons was acting in an unusually strange manner just before midnight when someone at his Hollywood Hills home became sufficiently alarmed to call 911. Paramedics rushed to the home and evaluated Richard, determining he should go to a hospital for evaluation.

We're told Simmons agreed to be taken to the hospital and he was transported to Cedars Sinai.

We do not know if Simmons is still hospitalized.

As TMZ has been reporting, Simmons has been a virtual recluse for 3 years ... shunning many friends and family.