Melatonin can now be sold over the counter in Australia, enabling insomniacs over 55 safer access to the sleep drug without a prescription.

Australians insomniacs aged over 55 will no longer need to look overseas to source a sleep-inducing drug without a prescription.

Melatonin is now able to be sold over the counter in Australian pharmacies after last year garnering the approval of the nation's medicines regulator.

The natural hormone is released by the brain each night in response to darkness, helping to induce and maintain sleep.

But leading pharmacist John Bell said people's natural supply of melatonin depletes as they age and can lead to poorer sleep.

"Melatonin is considered safe for short-term use," he said in a statement on Wednesday.

"In contrast to many sleep medications, with melatonin people are unlikely to become dependent, have a diminished response after repeated use (habituation), or experience a hangover effect."

Deloitte Access Economics in 2011 estimated the indirect cost of sleep disorders include $3.1 billion in lost productivity due to premature workforce separation, death, and absenteeism.

Seeking some extra shut-eye, melatonin prolonged-release tablet brand Circadin said some Australians have previously sourced the supplement from overseas to bypass the need for a prescription.

As former national president of the Pharmaceutical Society of Australia, Mr Bell indicated purchasing unregulated melatonin products could compromise user safety.

"If the country of origin from which some Australians have been purchasing melatonin products does not have the same regulatory excellence as Australia, there is no way to check the products are safe, of a high quality and do what they are supposed to do," he said.

The new over-the-counter availability is only a short-term treatment for people over 55, and must be ticked off by a pharmacist.