BOSTON -- There are new concerns about the amount of sleeping pills Americans are taking these days.

About 42 million sleeping pill prescriptions were filled last year. That's a 60 percent increase over the year 2000.

Some experts worry the drugs are being overprescribed without enough regard for side effects or implications of long-term use.

More people are also turning to a new generation of sleep aids such as Ambien and Lunestra. Some researchers said these new sleep aids can sometimes cause strange side effects, such as sleepwalking and short-term amnesia.

Ambien's maker said the drug is effective and safe when taken as prescribed.