Spears was rushed to UCLA Medical Center at about 1:30 am (0930 GMT) and was to be placed on a 5150 hold, the involuntary confinement of a person deemed to be a danger to themselves or others.
A psychiatrist treating the singer contacted Los Angeles police to set the events in motion, TMZ said, citing "law enforcement sources."
The troubled singer was stripped of access to her two baby boys at the beginning of the month, after she was rushed to hospital on a stretcher amid fears for her health.
During that incident Spears was wheeled out of her home on a stretcher following a stand-off which began when she reportedly refused to release her two children, Sean Preston, 2, and Jayden James, 1 to ex-husband Kevin Federline's bodyguard.

Copyright AFP (Agence France-Presse), 2008