A new drug for treating insomnia has shown promise in a preliminary study.

The drug called suvorexant works by blocking messengers in the brain known as orexins that induce wakefulness.

The study, funded by Merck Research Laboratories, involved 254 people aged between 18 and 64. All the participants suffered from insomnia that wasn't due to any other medical condition.

Study participants were randomly assigned to either get a dose of placebo or the drug for four weeks. They were then given a different treatment for insomnia. Participants' sleep was monitored in a sleep lab on the first day of the treatment and once again after four weeks.

Study results showed that participants who took the drug had improved sleep efficiency of 5 to 13 percent when compared to those who took placebo. Sleep efficiency is the total amount of time that the participants slept in a fixed 8-hour period.

"This study provides evidence that suvorexant may offer a successful alternative strategy for treating insomnia. Suvorexant was generally well-tolerated, and there were no serious side effects," said study author W. Joseph Herring, of North Wales, Penn., Executive Director of Clinical Research with Merck.

People on the drug also spent 21 to 37 fewer minutes awake during the 8-hour sleeping period.

"The amount of additional sleep was not tremendous," said Dr. Carl Bazil, director of the division of epilepsy and sleep at New York-Presbyterian Hospital/Columbia University Medical Center, HealthDay reported.

Bazil added that the drug might be more effective in inducing sleep when compared to other drugs because it specifically targets brain messengers that keep the person awake. The other drugs act on the entire brain that leads to many side-effects.

"The way [suvorexant] works makes a lot of sense. The hope is that it will help some people who haven't responded to [other drugs], and have fewer side effects," Bazil added.

The study is published in the journal Neurology.