The Food and Drug Administration, as part of its continuing probe of over-the-counter drugs, yesterday called for a ban on the active ingredient in virtually all non-prescription nighttime sleep aids, claiming the substance may cause cancer in animals.

In another, action stemming from the same investigation, the FDA followed up on an earlier statement of Commissioner Donald Kennedy, and called for the end of marketing of daytime sedatives.

Further, the FDA ruled that caffeine is the only safe and effective non-prescription stimulant. The agency said labels on any stimulants sold over-the-counter should reflect the fact that they contain about as much caffeine as a cup of coffee, and should be taken cautiosly with other products containing caffeine, like coffee or cola drinks.

In the case of the nighttime sleep aids, such as "Nytol," "Excedrin PM." "Sominex," "Compoz," and "Sleep-Eze," the FDA contends that the ingredient Methapyrilene, the most commonly used antihistamine in those products, was found by the National Institute of Cancer, to possibly cause cancer in laboratory animals.

FDA spokesman Wayne Pines said the agency wants to impose the ban on sales of such products until a study of possible carcinogenic links is completed.

After 60 days of public comment, the final regulation would be drafted and issued, and go into effect 60 days thereafter.

The agency did say, however, that it would allow a similar substance known as Pyrilamine to be used in the over-the-counter sleeping pills while further studies are conducted.Presidently, no drug in the sleep aids meets FDA requirements for safety and effectiveness.

The FDA ruled that any sleep aids that remain on the market must be labeled as follows: "helps fall asleep," "for relief of occasional sleeplessness," or "helps to reduce difficulty in falling asleep." There will also be a required statement warning against use of the drugs with alcohol.

As to the daytime sedatives, like "Compoz," "Tranquium, "Cope" and "Miles Nervine," the FDA action would not call for the products to be taken off the market, but instead would prohibit their promotion as sedatives.

The action seeks to restrict all advertising, labeling and other promotion of such products. The FDA said the products "provide no sedation, but merely make people drowsy when they may not want to be - i.e., while driving an automobile or operating machinery."

Last June, Kennedy said that daytime sedatives should not be promoted as such, based on early studies by a panel of experts studying over-the-counter drugs.

For products containing caffeine, the FAA is proposing a label that would say: "Helps restore mental alertness or wakefulness when experiencing fatigue or drowsiness."

The Proprietary Association, a trade group for the over-the-counter drug industry, said it is opposing the FDA ban on methapyrilene because the evidence is "insufficient to warrant taking it off the market."