WASHINGTON -- Federal health regulators say an experimental insomnia drug from Merck can help patients fall asleep, but it also carries worrisome side effects, including daytime drowsiness and suicidal thinking.

The Food and Drug Administration review of the company's sleep aid, suvorexant, noted that company trials show suvorexant is better than a placebo at helping people fall asleep and stay asleep. And regulators said the drug's effectiveness was consistent across several doses tested by Merck & Co. Inc.

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But patients taking the higher doses of the drug showed an eightfold increase in daytime drowsiness, which sometimes interfered with driving the next morning.

The FDA review also notes that suvorexant was associated with increased risk of suicidal thinking. -- AP