Sleep yourself slim and healthy

Readers of a certain age may remember the Bon Jovi song ‘I’ll Sleep When I’m Dead’, which featured the immortal lyrics “This ain’t no slumber party/
Got no time for catching z’s/If they say that that ain’t healthy/Well then living’s a disease… Gonna live while I’m alive/I’ll sleep when I’m dead.”

Hopefully Jon Bon Jovi and the rest of the band have grown up a little since the 1990s, but if not, they might want to rethink their cavalier position on sleep in the light of a study published in Current Biology in February 2019, which tested the effects of sleep loss with or without catch-up sleep on the weekend, on the metabolic health, food intake and weight gain of healthy young volunteers.

It turns out that if you really want to live while you’re alive, putting a high priority on securing sufficient sleep, 7 days a week, is a much smarter move than ‘seven days of Saturday’, done rock star style.

The study, whose title rolls trippingly off the tongue – ‘Ad libitum Weekend Recovery Sleep Fails to Prevent Metabolic Dysregulation during a Repeating Pattern of Insufficient Sleep and Weekend Recovery Sleep’ – recruited healthy young men and women to spend 12 nights in a sleep laboratory, and after 3 nights of establishing baseline conditions, randomised them into 3 groups:

1. Control: 8 lucky people (4 men, 4 women) were given 9 hours to sleep each night, and allowed to sleep as long as they wanted to for the next 9 nights.
2. Sleep restriction without weekend recovery sleep: 14 rather less lucky people (7 men, 7 women) were allowed to sleep for only 5 hours each night for 9 nights.
3. Sleep restriction with weekend recovery sleep: another 14 people (again, 7 men and 7 women) were allowed to sleep only 5 hours a night for 5 days, then permitted to ‘sleep in’ for as long as they wanted for 2 days, then restricted to 5 hours of sleep for the next 2 nights.

The researchers were particularly interested in the effect of these varying sleep schedules on markers of metabolic health (whole-body, muscle and liver insulin sensitivity), as well as participants’ circadian rhythm, sleep architecture, food intake and body weight.

The results should sound alarm bells to anyone who is routinely short-changing themselves on sleep… including parents of teenagers whose nocturnal social media usage results in morning grogginess on school days, and marathon sleep-ins on weekends.

Here are the key findings:

Metabolic health:

Whole-body insulin sensitivity decreased by a whopping 13% in the poor souls who were subjected to 9 nights of insufficient sleep – a huge concern given that the participants were healthy young people. Loss of insulin sensitivity can ultimately result in type 2 diabetes – a condition that used to be called ‘late onset diabetes’ because it only ever occurred in middle aged and elderly people, but is now being diagnosed in teenagers and even children.

In participants who were allowed to sleep in for 2 days after 5 days of sleep restriction, whole-body, hepatic, and muscle insulin sensitivity declined by between 9% and 27% compared to baseline when they were put back on restricted sleep for 2 nights – that is, 2 days of ‘catch up’ did not correct the metabolic dysregulation that 5 nights of insufficient sleep had created.

Energy intake and weight:

Participants in the sleep-restricted group also ate around 500 extra calories (concentrated in the after-dinner period), while those allowed to catch up on weekends tended to eat more pre-dinner snacks; both groups gained weight – an average of 1.4 kg in the continuous sleep-restriction group, and 1.3 kg in the weekend catch-up group – by the end of the study. Interestingly, the control group also ate more than usual during the study, but did not gain weight.

The weekend sleep-in was enough to help participants in condition 3 cut down on their after-dinner munchies, but when they were subsequently restricted to 5 hours of sleep for the following 2 nights, they overate after dinner again, and started regaining weight.

Sleep duration, sleep architecture and circadian rhythm:

Those who were allowed to sleep in on the weekend ending up only sleeping for an extra 1.1 hours compared to the sleep restriction phase (i.e. just over 6 hours, vs 5 hours on the previous 5 nights). Their circadian rhythms (‘body clocks’) were so thrown out by being allowed extra weekend sleep that they had trouble getting to sleep on Sunday evening, and stayed up later even though they knew they only had 5 hours to sleep.

Analysis of participants’ sleep architecture showed, as expected, reduced slow wave sleep (the type of sleep required for recovery of the brain from its daily activities) during the nights of restricted sleep, and a rebound increase in slow wave sleep on nights when group 3 participants were allowed to catch up on sleep. However, slow wave sleep was still increased on the night following the 2 day catch-up period, indicating that participants had not ‘paid off’ their sleep debt after 2 nights of unrestricted sleep.

Interestingly, women assigned to the weekend sleep-in condition got less sleep than men, but men still overate on the weekend while women’s energy intake returned to baseline levels.

The authors concluded that

“Under conditions of ad libitum energy intake [i.e. allowing participants to eat as much as they desired], our findings suggest that ad libitum weekend recovery sleep [i.e. being allowed to sleep in as long as desired] is not likely an effective countermeasure strategy to prevent the negative metabolic consequences associated with recurrent insufficient sleep across multiple workweeks.”

Or in plain English, if you think that sleeping in on the weekends makes up for not getting enough sleep during the working week, you are dead wrong – and your body and brain are paying for your mistake.

Specifically, routinely short-changing yourself on sleep makes you more likely to

• Overeat at night;
• Gain weight;
• Develop insulin resistance which may lead to metabolic syndrome and eventually, type 2 diabetes; and
• Suffer compromised recovery of your brain from its daytime activities, which may increase your risk of developing dementia.

The bottom line: For optimal health, eating well and exercising regularly is not enough. Ensuring that you get sufficient sleep in order to wake spontaneously, feeling refreshed, is crucial for you to be at your best now, and to reduce your future risk of chronic disease.

Do you struggle to get off to sleep, or wake up in the wee hours and lie awake? There are effective interventions for dealing with both these common forms of insomnia. Apply for a Roadmap to Optimal Health Consultation today, and let’s get you sleeping like a champion!