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Time of day crucial to accuracy of disease tests

New findings could be crucial when assessing the best time of day to test for diseases and administer medicines.

A new study, conducted by researchers from the University of Surrey, the Erasmus MC University Medical Centre in Rotterdam and The Institute of Cancer Research, has found that the time of day and sleep deprivation have a significant effect on metabolism.

The research, published in the Proceedings of the National Academy of Sciences (PNAS), is likely to be important in interpreting the results of blood tests, and in understanding why some individuals respond differently to medication.

Funded by a grant from the Biotechnology and Biological Sciences Research Council (BBSRC), the research put healthy male volunteers in an environment where light, sleep, meals and posture were controlled. Researchers collected blood samples every two hours to analyse how metabolic biomarkers changed during the day.

For the first 24 hours, the participants experienced a normal wake/sleep cycle. This was followed by 24 hours of wakefulness, to investigate the effect of sleep deprivation on metabolic rhythms.

The results showed that metabolic processes are significantly increased during sleep deprivation. 27 metabolites, including serotonin, were found at higher levels in periods of sleep deprivation compared to levels during sleep.

Lead author Professor Debra Skene from the University of Surrey, said: “Our results show that if we want to develop a diagnostic test for a disease, it is imperative to take the time of day when taking blood samples into account, since this has a significant effect on metabolism.

“This is also key for administering medicines and determining when they will be at their most effective. Of course, this will have to be considered on a case-by-case basis, since many people such as shift workers will have a different sleep/wake cycle and timings will need to be adapted to their body clocks.”

Discover more about programmes and research in the field of Biosciences and Medicine at the University of Surrey.

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