The truth about lie-ins

They will not repay your sleep debt if you burn the candle at both ends during the week

A FEW extra hours of shut-eye on your days off work are not enough to offset your “sleep debt” of late nights and early mornings during the week, a new study warns.

Insufficient sleep and untreated sleep disorders put people at increased risk of health problems, including obesity and diabetes.

Researchers set out to discover whether extra sleep at weekends is enough to reduce the risks.

The short answer, according to the findings published in the journal Current Biology, is no.

Study co-author Dr Kenneth Wright, of the University of Colorado, US, said: “The key takehome message from this study is that ad libitum weekend recovery, or catch-up sleep, does not appear to be an effective countermeasure to reverse sleep loss-induced disruptions of metabolism.”

People often sleep more over the weekend than they do during the week.

But it wasn’t known how returning to an insufficient sleep schedule during the working week after a weekend of recovery kip influences a person’s metabolic health. To find out, a University of Colorado team enlisted healthy young adults.

Each participant was randomly assigned to one of three groups. The first had plenty of time to sleep (nine hours) each night for nine nights.

The second had just five hours to sleep each night over that same period. The third group slept five hours for five days, followed by a weekend in which they slept as much as they liked before returning to another two days of restricted sleep.

In the two sleep-restricted groups, insufficient sleep led to an increase in snacking after dinner and weight gain.

During weekend recovery sleep in the third group, study participants slept an hour longer on average than they usually would. They also consumed fewer extra calories after dinner than those who got insufficient sleep.

But when they went back to getting insufficient sleep after the weekend, their circadian body clock was timed later. They also ate more after dinner as their weight continued to rise.

The sleep restriction in the first group of participants was associated with a decrease in insulin sensitivity of about 13%, according to the findings.

But the group that had a chance to sleep more on the weekend still showed less sensitivity to insulin.

The insulin sensitivity of their whole bodies, liver and muscle decreased by 9% to 27% after they got insufficient sleep again, once the weekend was over.

Study co-author Dr Christopher Depner, an assistant professor, said: “Our findings show that muscle- and liver-specific insulin sensitivity were worse in subjects who had weekend recovery sleep.”

He noted that those metabolic aberrations weren’t seen in the people who got less sleep all along.

“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.”

The Sleep Research Society and American Academy of Sleep Medicine recommends seven or more hours of sleep nightly for adults to promote optimal health.

The new findings add to evidence that insufficient sleep is a risk factor for metabolic disorders.

The researchers said that their study also shows that catching up at weekends isn’t the solution to chronic sleep loss during the week.

Wright added that it’s not yet clear whether weekend recovery sleep can be an effective health countermeasure for people who get too little sleep only occasionally.

He said the team hopes to explore the fine details of these dynamics in future studies, including the influence of daytime napping and other strategies for getting more sleep.

In the two sleep-restricted groups, insufficient sleep led to an increase in snacking after dinner and weight gain.