The experimental drug tasimelteon has passed its second late-stage trial with surprisingly good results, showing the effectiveness of the drug in treating a rare condition called non-24-hour sleep-wake disorder (non-24).

Non-24 is a serious cicardian rhythm sleep disorder characterized by hourly delays in sleep onset and wake times due to a person’s body clock not properly adjusting to the light/dark cycle. This results in people being unable to sleep at night and then feeling exhausted and tired during the day. It is a somewhat rare disorder, only affecting an estimated 1 in every 2,000 people – although quite common among blind people. As of yet, there isn’t any approved form of treatment.

The drug developed by Vanda regulates the circadian rhythm, acting as a melatonin agonist. It works by resetting a person’s master body clock in the hypothalamus, which stabilizes the melatonin and cortisol rhythms to a regular 24-hour day-night cycle.

The RESET study was carried out to evaluate the efficacy and safety of the drug in treating people with 24-hour.