Sleep is an integral part of our lives; we need to have a certain amount of sleep on a daily basis to be able to get back to life. Having less sleep than is needed comes with consequences. A new study, published in the journal Proceedings of the National Academy of Sciences, has investigated the effects of curtailing one’s hours of sleep, bringing about the phenomenon known as sleep debt.
The aim of the study was to understand the molecular mechanisms brought about by chronic sleep restriction.
The researchers recruited healthy individuals for the study, and included lab rats for the experiments. They subjected both groups to sleep restriction, that is, the participants were not deprived of sleep completely, but their sleeping hours were limited. They were made to sleep for only four hours every night for five days.
Amita Sehgal, one of the authors, explained the occurrence of “sleep restriction” in the following words:
“Sleep restriction more closely represents real-world situations in humans and is a condition experienced by millions of people every day“.
In the past, not having adequate sleep has been linked with metabolic disorders like weight gain, diabetes, obesity and heart problems. This would imply that we need sleep for important reasons.
“One possibility is that sleep drives metabolite clearance and so acts as a reparative process at the metabolic level,” explained researcher Sehgal.
Sehgal and the team set out to compare the metabolites (the end products of metabolism) among those rats and humans having slept well and those who have not. The serum of all the participants was analysed.
It was found that 50 % of the metabolites particular to sleep-restricted rats were lipids, and most of those from their human counterparts were either lipids or fatty acid-related substances.
When these were compared to the subjects having had adequate sleep, it was observed that those with restricted sleep (both humans and rats) showed significant decreased concentrations of oxalic acid (a byproduct of processing food and the breaking down of vitaminc C and amino acids) and diacylglycerol 36:3 (a precursor in the synthesis of triglycerides for the storage of fats) and increased levels of phospholipids.
Interestingly, the two depleted metabolites (oxalic acid & diacylglycerol 36:3) were restored after recovery sleep.
The researchers are of the opinion that these could be cross-species biomarkers of sleep debt.
However, they could not quite explain the increase in phospholipids.