Shift workers continue taking alertness drugs despite the lack of strong evidence confirming its benefits, a new study finds.

Sleep inducing and alertness drugs have become very popular among shift workers. What's concerning is that there is very little evidence that suggests these drugs do any good. Throwing more light on this subject, a team of researchers conducted a new study and found only a small numbers of trials on the use of over-the-counter and prescription drugs among shift workers. Most of these studies noted that such drugs have more negative effects than positive ones.

For the study, researchers reviewed 15 trials involving a total of 718 people. In nine trials, the over-the- counter hormone drug melatonin helped shift workers sleep for around 24 minutes longer during the night or day, compared to placebos. However, these drugs didn't help them to fall asleep quicker. One drug named zoplicone was no more effective than placebos for helping shift workers sleep during the day.

The remaining six trials analyzed how caffeine and two drugs, modafinil and armodafinil help shift workers stay awake at night. One trial showed that caffeine was effective in keeping sleep at bay, only when the workers napped before their shift. The drugs were also found to increase alertness and reduce sleepiness.  However, they were accompanied by their fair share of side effects including headaches, nausea and a rise in blood pressure.

"For lots of people who do shift work, it would be really useful if they could take a pill that would help them go to sleep or stay awake at the right time," said lead author Juha Liira, said in a press statement. "But from what we have seen in our review, there isn't good evidence that these drugs can be considered for more than temporary use and some may have quite serious side effects."

"It's curious that there's such a clear gap in the research," said Liira. "It may well be that studying the effects of these drugs or others drugs in properly designed trials would be seen as unethical because workers should not need drugs to get along with their work. So the studies just haven't been done or if they have, our review has not been able to identify relevant data."

Findings were published online in The Cochrane Library.