Sydney, Aug 29 (IANS): A simple coffee and a quick short sleep afterwards (called caffeine-nap) could be the cure to stay alert on night jobs as a new study shows that this unlikely combination can improve attention and reduce sleep inertia.

Shift workers are often chronically sleep-deprived because they have disrupted and irregular sleep patterns.

"As a result, they commonly use a range of strategies to try to boost their alertness while on the nightshift, and these can include taking power naps and drinking coffee," said study author Stephanie Centofanti from the University of South Australia.

The findings, published in the journal Chronobiology International, could help counteract the kind of sleep inertia that is experienced by many shift workers.

According to the researchers, many workers nap during a night shift because they get so tired.

But the downside is that they can experience 'sleep inertia' and this can impair their performance and mood for up to an hour after their nap.

"Caffeine is also used by many people to stay awake and alert. But again, if you have too much coffee it can harm your overall sleep and health," Centofanti said.

If you use it to perk you up after a nap, it can take a good 20-30 minutes to kick in, so there's a significant time delay before you feel the desired effect.

A 'caffeine-nap' (or 'caff-nap') could be a viable alternative - by drinking a coffee before taking a nap, shift workers can gain the benefits of a 20-30-minute nap then the perk of the caffeine when they wake.

The small pilot study tested the impact of 200 mg of caffeine (equivalent to 1-2 regular cups of coffee) consumed by participants just before a 3.30 am 30-minute nap, comparing results with a group that took a placebo.

Participants taking a 'caffeine-nap' showed marked improvements in both performance and alertness, indicating the potential of a 'caffeine-nap' to counteract sleep grogginess.

The researchers noted that this shows a promising fatigue countermeasure for shift workers. Centofanti said that the next move is to test the new finding on more people.