Instead of blood tests, now all that is needed is a simple mouth swab.

The technique could aid studies into Attention Deficit Hyperactivity Disorder (ADHD) and the effectiveness of chemotherapy at certain times.

The test indentifies genes that regulate sleep, and first test samples were taken on Thursday at a science festival.

The natural pattern of wake and sleep is known as the circadian rhythm.

A number of different genes control an individual's circadian rhythm and the levels of ribonucleic acid (RNA) produced by these different genes indicate how active they are at different times of day.

One gene known as Per2 produces the highest levels of RNA at about 4am, and is the gene associated with sleep.

The gene examined at the science festival in Cheltenham produces its highest levels at about 4pm, is known as REV-ERB and is thought by scientists to be associated with wakefulness.
Samples were taken before and after a talk at the festival and are being analysed by the Swansea researchers. The results will be made available to individuals online.

Sarah Forbes-Robertson, a research fellow at Swansea university, said if a person produces higher levels of REV-ERB before 4pm they are likely to be an early bird.

If someone produces higher levels after 4pm they are likely to be a night owl.

Paul Barnett, a freelance music promoter from Cardiff, said he had always been a natural night owl and would be even if he worked in a job without so many late nights.

"I get up at around 9 or 9.30 and don't go to bed until 1am. It's always been this way and it drives me mad!" he said.

"One of my former relationships was with a teacher and she went to bed at 11pm but I was never tired enough. It had an impact on the relationship."

Sleep pattern

Early riser Stephen Chant, a Royal Mail delivery office manager in Cardiff, said he has never got used to the early morning starts required in his job but he is in a pattern.

"I still wake up early in the morning at the weekend and it drives my wife potty," he explained.

"I would say I have become an early riser. I've had to discipline and condition myself to it and that means I have had to make sacrifices like not having a drink - even a pint - in the week."
Scientists believe the swab technique will open up their field of research because the individuals tested can continue with their normal day and night activities.

Previously samples would need to be taken every four hours over a full day and night.

It will also allow researchers to assess whether jet lag cures, like melatonin tablets, actually do anything to alter gene expression.

"Gene expression can be altered by external factors, such as jet lag," said Ms Forbes-Robertson.

"One interesting finding is that food affects gene expression. So, after lunch, Per2 has a small peak, leading to that post lunch slump," she noted.

BBC