Losing Sleep = Gaining Pounds

When it comes to gaining or losing fat, then generally people focus a lot more on movement than on sleep.

And movement is great! See for example: The Doctor Who Wants Us To Exercise Less, & Move More

But it’s nothing without adequate sleep, because…

You snooze, you lose (pounds)

Researchers (Dr. Marie-Pierre St-Onge et al.) pooled randomized trials and found that reducing nightly sleep by about 80 minutes for 6 weeks led to an increase in weight and increased sedentary behavior.

That lost sleep is bad for the health is not, in and of itself, breaking news. See for example: What Harm Can One Sleepless Night Do? and Why You Probably Need More Sleep ← yes, including if you are in the older age range; we bust that myth in the article too!*

^{*Unless you have a (rare!) mutated ADRB1 gene, which reduces that. But we also cover that in the article, and how to know whether you have it.}

However, previous research mainly examined extreme sleep deprivation of around 4 hours per night for only a few days, whereas this study investigated the milder, chronic sleep loss that is much more common in everyday life.

What they did: 95 adults who normally slept 7–8 hours per night completed two 6-week phases; one with their usual sleep schedule, and another in which they delayed their bedtime by 90 minutes (in principle; in fact it was more like 78.4 minutes on average) while wearing wrist monitors to measure sleep and activity (which is where we got the 78.4 minutes figure from). Dr. St-Onge and her team then also tracked body weight, waist circumference, body composition, fasting appetite-related hormones, sleep duration, and physical activity.

The results were clear:

❝Body weight (0.45 kg [CI, 0.33 to 0.57 kg]), waist circumference (0.52 cm [CI, 0.25 to 0.79 cm]), and whole-body volume (0.56 L [CI, 0.19 to 0.93 L]) were increased with SR relative to AS. Leptin levels were elevated with SR versus AS (2.03 ng/mL [CI, 0.38 to 3.68 ng/mL]). Sedentary time was increased by 17.2 minutes (CI, 11.7 to 22.7 minutes) per day with SR versus AS.❞

AS = adequate sleep
SR = sleep restriction

In words: participants in general spent an average of 17 additional minutes per day being sedentary during the sleep-restriction phase, while men and postmenopausal women increased their sedentary time by nearly 30 minutes per day. To be clear, the increase in sedentary time wasn’t simply a case of participants being awake longer, as they were proportionally less active when they slept less.

This does mean that because prolonged sedentary behavior is associated with chronic disease, the increased inactivity (resultant from tiredness) itself may (and almost certainly does) contribute to the health risks famously linked with insufficient sleep.

Indeed, a previous study involving a subset of the same participants found that similar mild sleep restriction increased insulin resistance in women with elevated cardiometabolic risk, particularly postmenopausal women, and increased inflammatory cells in the hearts of both men and women with elevated heart risk.

As for this one, you can read in full here: Prolonged Short Sleep and Its Effect on Body Weight and Composition: A Pooled Analysis of Randomized Trials

Want to learn more?

If the name of Dr. Marie-Pierre St-Onge rang a bell, it may be because we’ve featured her before in our “Expert Insights” section:

The 6 Dimensions Of Sleep (And Why They Matter)

And for more on sleep in general, we’ve written a lot, but here are a few to get you started:

How Regularity Of Sleep Can Be Even More Important Than Duration ← here’s why you should still get up at the same regular (and ideally, early) hour, even if you didn’t sleep well

Early Bird Or Night Owl? Genes vs Environment ← and here’s why that regular hour should ideally be early, even if it’s not your genetic predisposition to be a “morning lark”; see also the study linked there that mentions “Gene distinguishes early birds from night owls and helps predict time of death”

Some sleep aids can help, but many are harmful and/or do not really work as such; here’s a rundown of examples of those:

Safe Effective Sleep Aids For Seniors?

And when it comes to napping, timing is everything:

How To Nap Like A Pro (No More “Sleep Hangovers”!)

Sweet dreams!