If a person who is a patient hospitalized under section
322 or
324 of this title, or his legal guardian, spouse, or adult next of kin, requests the release of such patient, the right of the Secretary, or the head of the hospital, to detain him for care and treatment shall be determined in accordance with such laws governing the detention, for care and treatment, of persons alleged to be mentally ill as may be in force and applicable generally in the State in which such hospital is located, but in no event shall the patient be detained more than forty-eight hours (excluding any period of time falling on a Sunday or legal holiday) after the receipt of such request unless within such time