Researchers from the University of Surrey and The Institute of Cancer Research, London, investigated the links between sleep deprivation, body clock disruption and metabolism, and discovered a clear variation in metabolism according to the time of day.
Healthy male volunteers were put in an environment where light, sleep, meals and posture were controlled.
Researchers collected blood samples every two hours to show how metabolic biomarkers change during the day. For the first 24 hours, the participants experienced a normal wake/sleep cycle.
Twenty-seven metabolites, including serotonin, were found at higher levels in periods of sleep deprivation compared to levels during sleep.
"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," said lead author Professor Debra Skene from the University of Surrey.
"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," Skene said.
"Our findings are likely to be important in interpreting the results of blood tests, and in understanding why some individuals respond differently to medication.
"They also set reference points for future studies looking at the connection between metabolic processes and diseases such as cancer," Raynaud said.
The study was published in the journal PNAS (Proceedings of the National Academy of Sciences).