As I sit here writing to you, it’s 2.43am.
I’ve been awake for the last 45 minutes.
All the “sleep hygiene” boxes have been ticked.
The room is dark and quiet.
There are no electronic gadgets in there.
I have nothing on my mind that I’m trying to remember to remember.
But, for reasons that remain mysterious, I cannot get back to sleep.
It makes no sense, especially given that the exact opposite will often happen when I’m sat in a meeting.
The lights in the room are on.
People are talking.
I am nodding my head sagely.
And yet it’s only “meeting etiquette” that stops me falling into the warm and comforting embrace of an afternoon nap.
Rather than waste any more time tossing and turning in bed, I thought I’d write to you about the negative impact that sleep deprivation can have on your ability to lose fat and build muscle.
As you probably know already, lack of sleep doesn’t do great things for your mood. But a single night of missed sleep is unlikely to harm your performance in the gym.
In one trial, researchers from Midwestern State University found that going an entire night without sleep had no effect on training performance in a group of collegiate weightlifters .
Although total mood disturbance was increased by sleep deprivation, the men were able to lift just as much as weight as they did following a night of normal sleep.
Where sleep deprivation does make it harder to get in shape is by affecting both hunger (the physical need for food) and appetite (the desire for food).
Researchers aren’t sure exactly how it happens.
Some studies show that sleep deprivation disrupts some of the hormones (leptin and ghrelin in particular) that affect your eating habits. Brain cells involved in the modulation of reward and motivation may also be altered by restricting sleep.
The result is that you end up eating far more than normal. In some trials, subjects who were deprived of sleep ended up munching their way through the best part of 600 extra calories per day .
In other words, a lack of sleep makes it a lot harder to control your appetite, especially for high carbohydrate “junk foods” like sweets, cookies, chips and so on .
Sleep deprivation isn’t great news for your testosterone levels either.
A group of young men spent three nights in a sleep lab, sleeping for up to 10 hours . For the next eight nights, their sleep was restricted to just five hours per night. Daytime testosterone levels dropped by 10% to 15%.
A follow-up study found no significant effect of sleep restriction on testosterone . But there was a trend towards a decrease, which may have been greater had the sleep restriction phase of the study lasted longer than five nights.
It gets worse.
Another study I looked at shows that overweight adults on a diet lost 60% more muscle with 5.5 versus 8.5 hours of “sleep opportunity” per night .
Both groups followed the exact same diet, losing an average 6.6 pounds during each 14-day session. During weeks with adequate sleep, roughly half of the lost weight came from fat and half from fat-free mass. But during the short-sleep weeks, participants lost an average of 1.3 pounds of fat and 5.3 pounds of fat-free mass.
When sleep was restricted, dieters produced higher levels of ghrelin, a hormone that triggers hunger and reduces energy expenditure.
Higher ghrelin levels have been shown to “reduce energy expenditure, stimulate hunger and food intake, promote retention of fat, and increase hepatic glucose production to support the availability of fuel to glucose dependent tissues,” the authors note. “In our experiment, sleep restriction was accompanied by a similar pattern of increased hunger and reduced oxidation of fat.”
Granted, this was a short trial lasting 14 days. And nobody taking part lifted any weights or ate enough protein. But the research does hint at the possibility that sleep deprivation could make it harder to retain muscle while you drop fat.
So there you have it.
I’m probably not going to be in the greatest mood for the rest of the day.
When I go to the gym in around seven hours time, I should still be able to hit the rep targets in the Muscle Evo spreadsheet.
But the chances are very high that at some point this afternoon I’m going to be hit with the urge to eat the entire packet of custard creams currently sat in my cupboard.
SEE ALSO: THE FLAT BELLY CHEAT SHEET
If you want less flab and more muscle when you look down at your abs (or where they should be), check out The Flat Belly Cheat Sheet.
It's a “cut the waffle and just tell me what to do” PDF, written in plain English, that tells you exactly how to get rid of belly fat. To download a free copy please click or tap here.
ABOUT CHRISTIAN FINNChristian Finn holds a master's degree with distinction in exercise science, is a former personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Fit Pro, Zest, and Perfect Body magazine.
1. Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. (2010). Insufficient sleep undermines dietary efforts to reduce adiposity. Annals of Internal Medicine, 153, 435-441
2. Blumert PA, Crum AJ, Ernsting M, Volek JS, Hollander DB, Haff EE, Haff GG. (2007). The acute effects of twenty-four hours of sleep loss on the performance of national-caliber male collegiate weightlifters. Journal of Strength and Conditioning Research, 21, 1146-1154
3. Brondel L, Romer MA, Nougues PM, Touyarou P, Davenne D. (2010). Acute partial sleep deprivation increases food intake in healthy men. American Journal of Clinical Nutrition, 91, 1550–1559
4. St-Onge MP. (2013). The role of sleep duration in the regulation of energy balance: effects on energy intakes and expenditure. Journal of Clinical Sleep Medicine, 9, 73-80
5. Leproult R, Van Cauter E. (2011). Effect of 1 week of sleep restriction on testosterone levels in young healthy men. JAMA, 305, 2173-2174
6. Reynolds AC, Dorrian J, Liu PY, Van Dongen HP, Wittert GA, Harmer LJ, Banks S. (2012). Impact of five nights of sleep restriction on glucose metabolism, leptin and testosterone in young adult men. PLoS One, 7, e41218
7. Spiegel K, Leproult R, Van Cauter E. (1999). Impact of sleep debt on metabolic and endocrine function. Lancet, 354, 1435-1439