If you're averaging anything less than seven to eight hours' sleep a night, you could be racking up sleep debt. This is when your body needs more sleep to recover from previous nights of bad sleep. You might think that having a lie-in every weekend would solve your lack of sleep during the week. But a new study has found that catching up on sleep at the weekend actually does little to help and could actually be having a negative impact on your overall health.
According to the NHS, lack of sleep can increase your risk of developing several metabolic health issues, including diabetes. Researchers from the University of Colorado Boulder wanted to see whether so-called "recovery sleep" could improve a person's metabolic health and effectively pay off the sleep debt they'd built up during the working week.
A group of healthy young adults took part in the study, which was published in the Current Biology journal. Each person was randomly assigned to one of three groups. The first group had nine hours' sleep each night for nine nights in a row while the second were only given five hours' sleep each night. The third slept for five hours for five days and switched to sleeping for however long they wanted at the weekend. During the last two nights, they reverted back to restricted sleep.
Researchers studied participants' dietary intake. They found that those who had been sleep restricted throughout the entire period were more likely to snack after meals.
But the people who were selected for the weekend recovery group were less likely to snack. However, this effect was only seen at the weekend. When the participants in the final group went back to restricted sleep, they too began to snack more.
Insulin sensitivity was also measured. As Diabetes UK states, people with low insulin sensitivity will need larger amounts of insulin to keep blood glucose levels stable. This can also lead to a range of health problems such as high blood pressure and type 2 diabetes.
The second group of participants saw around a 13 percent drop in insulin sensitivity. And there were issues with insulin even in the group who were given a chance to catch up on sleep at the weekend. Researchers found that the insulin sensitivity of their entire bodies, liver, and muscle reduced by nine to 27 percent once they were back to restricted sleep.
"This finding was not anticipated and further shows that weekend recovery sleep is not likely [to be] an effective sleep-loss countermeasure regarding metabolic health when sleep loss is chronic," noted one of the researchers, Christopher Depner, in a statement. That's a fancy way of saying that spending your weekend compensating for lost sleep isn't doing anything for your help.
However, the study only looked at the effects of recovery sleep on those who were undergoing chronic sleep loss. Such an impact may not be seen in those who only sleep less one or two nights a week. The researchers are planning to delve more into the topic, including taking a look at how daytime napping affects health.
If you're worried by the findings, consider trying to sleep an extra hour every night. The NHS recommends around eight hours a night for adults, but does note that some people may need more and some may require less. If you're constantly tired, you're probably in the first group.