A blood test can tell if your body clock is screwed up

It has long been known that drugs work more effectively at particular times of the day, depending on the activity of certain genes when they are taken.

But because sleep disorders and other conditions can disrupt the circadian rhythm (or ‘body clock’), standard recommendations — for example to take medication for kidney disease later in the evening — don’t work universally.

Researchers from Vanderbilt University School of Medicine in the US have developed a blood test which they say shows the time of an individual’s body clock, by monitoring the activity of 15 specific genes.

This, they say, could allow for a new age of ‘chronotherapy’, in which the timing of medication is custom designed for every patient.

The blood test, details of which have been published in the journal Genome Medicine, was developed by studying which genes were active in blood samples taken from 60 participants at different times of the day.

The study’s lead author, Dr Jake Hughey, said: ‘Our study demonstrates a method for predicting a person’s internal time of day that could eventually be used to help diagnose and monitor circadian and sleep-related disorders, and also to personalise treatments.

‘In general the method would likely detect when someone’s clock is running early or late or maybe weaker than it should. As far as chronotherapy, I would say there are probably more opportunities for daily timing of treatments than we are currently taking advantage of.

‘I think over the next few years we will see more systematic efforts to define when chronotherapy really makes a difference. Methods like the one I describe could help us personalise the time of day of treatment, since everyone’s clock is a little different, and saying something like “7pm Eastern Standard Time” ignores those inter-individual differences.’

Instant analysis
This study is intriguing and the paradigm of ‘chronotherapy’ is a novel concept but the findings are somewhat limited by the median absolute error in circadian time of over two hours. This is hardly precision.

While there is a small number of subjects in the study, the statistical methodology seems otherwise reasonably robust.

The immediate relevance of this work seems to be the applicability of bespoke medication timing regimens to individuals based on their circadian time. This could potentially allow treatment to be temporally personalised and it may also facilitate the treatment and monitoring of sleep disorders.
JCH
Research score: 3/5