Suvorexant was tested in two studies that lasted three months and included about 2,000 adults. Krystal's team randomly assigned them to get suvorexant (in various doses) or a placebo.
The researchers studied objective measures gotten from the sleep lab and sleep tests. They also looked at subjective measures such as the patients' reports of the time it took to fall asleep and their total sleep time.
In both studies, patients taking suvorexant fell asleep faster and stayed asleep longer.
For instance, in one study, people on the sleeping pill at the three-month mark slept 60.3 minutes longer, on average, while those on placebo slept 40.6 minutes longer -- a difference of more than 19 minutes.
"Nineteen minutes a night of more sleep for an entire month is a lot of additional sleep," Krystal says.
In the same study, those on suvorexant fell asleep about 25 minutes faster than at the start of the study; those on placebo fell asleep about 17 minutes faster.
Those on the pill spent about 48 minutes less time awake during the night than before the medication, compared to 25 fewer minutes for those on the placebo. For the second study, results were similar. "The fact [that] there is benefit on the sleep study finding and the self reporting finding is critical," Krystal says.
No serious adverse events were found in either trial. The most common complaints were sleepiness and headache. All of the studies were funded by Merck.
In third study, which lasted a year and was also presented at the meeting, 522 men and women were given suvorexant and 259 got a placebo.
The new sleeping pill improved the total sleep time as reported by the patient by an average of 23 minutes. It reduced the time it took to fall asleep by 10 minutes.
David Neubauer, MD, associate professor of psychiatry at Johns Hopkins Medical Institutions, who has researched almorexant, reviewed the findings for WebMD.
"I think so far the clinical trials are very encouraging and warrant further investigation," he says.
The new drug reflects a new view of sleep problems, says Neubauer. "The new thinking is that insomnia is not just trouble sleeping at night, but a 24-hour disorder for many people," he says. "For many people it is a kind of round-the-clock hyper arousal."