Skin test can tell late from early risers

Hate getting up? It could be in your genes

A simple skin test could reveal if someone who hates getting up is just lazy or whether they are programmed to like lie-in.

Over recent years, scientists discovered that genes can influence whether a person has a preference for getting up extremely early (known as a ‘lark’), or later in the day (known as an ‘owl’).

Now, a skin test to diagnose people with these genes has been devised, which could help the development of treatments for people with sleeping disorders.

The reason that we want to go to bed or get up is to be controlled by a central ‘circadian’ clock, a part of the brain called the hypothalamus.

Today, a study in Proceedings of the National Academy of Sciences confirms the view that almost every cell in the body contains a clock. Professor Steve Brown and his colleagues at the Chronobiology and Sleep Research Group, University of Zurich, found that the brain’s hypothalamus acts as a central clock for the body, but does so by synchronising all the individual cells, which have their own clocks.

Skin cells are easier to study than brain cells, so the team obtained cells from 28 volunteers and inserted a gene that glowed in to them, creating biological clocks that beamed or waned over 24 hours.

The researchers found that skin cells of the early-risers had the shortest glow-time, while sleepyheads had the longest, concluding that their work could lead to treatments for patients with extreme circadian rhythms.

‘People know whether they are larks or owls,’ says Professor Brown. ‘The interesting part is that they are not all larks or owls for the same reason, and this research addresses the molecular cause of their early or late behaviour.

‘What is really nice here is that by looking at clocks in peripheral tissues, we have for the first time been able to look, by proxy, at the molecular mechanisms in different human individuals that allow them to sense time in the brain.’

He added: ‘Once the cause of a sleep disorder has been accurately diagnosed, it is possible to test treatments on patients who all have the same underlying disfunction, a key step towards developing more effective treatments for body clock disorders.’

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