As a society we have evolved in many different ways. One of the most striking changes has been how our activity levels have plummeted in the past hundred or so years. The average calorie expenditure has decreased continually as the modern conveniences of technology have taken us out of the fields and put us into offices.
The drawback with this convenience is that while our daily expenditure has dropped significantly, our caloric intake has risen. This has resulted in a society that is bigger, fatter and less active than our great, great grandparents.
The Decline Of Sleep
In 1910 on average we were getting approximately 9 hours of sleep per night. This has also dropped, with the pull of modern society dragging us down to approximately 7 hours of sleep per night. Spread out over the course of a year we are talking in effect of over 700 hours.
With the constant number of demands made on us from work, family, to friends to social commitments usually the first thing that we begin to cut back on is sleep. The reasons we are getting less sleep are varied and complex, but I will not touch on those in this article. Instead I will talk solely about the effect of sleep on our physical health and weight loss.
The Connection Between Sleep Deprivation and Weight Loss
Sleep deprivation doesn’t seem like a likely cause for obesity. After all, how harmful can it be if we skimp an hour off a night’s rest? But they are intrinsically linked.
According to a 2004 study, those who were getting less than 6 hours per night were 30 percent more likely to become obese than those who slept an average of 9 hours. Other clinical studies conducted by the National Sleep Foundation have shown that insufficient sleep is strongly connected with obesity, heart disease, and an elevated risk of diabetes.
The cause of this troublesome connection lies principally with two hormones our body produces – leptin and ghrelin. Leptin tells the brain to suppress appetite, while ghrelin gets the growl in your stomach going. Further, leptin and the hunger cravings that result from a lack of sleep produce cravings for the types of food that cause obesity – high-fat, sugar-laden foods and beverages (ahem, Red Bull).
How Much Sleep Should You Be Getting?
The reality is there is no magic number. It is difficult to know precisely how much is enough, and individual groups need more or less sleep than others. To make things a little more confusing, there are two factors that science is still trying to truly figure out – sleep debt, the amount of sleep that is lost to sickness, poor sleep habits etc, and a person’s basal sleep need, which is the amount of sleep that a person needs to achieve optimal performance.
For adults the sweet spot is generally between 7-9 hours. Obviously each individual is different. Keep a sleep journal and record how much sleep you are getting, and note what type of hunger pangs you have in the morning.
The Correlation Between Exercise and Sleep
It has long been considered dogma that exercise promotes better sleep at night. The belief was that when you spend more calories during the day you are more adept to needing more – and deeper – rest at night. I always felt this was the case. Particularly if I went a couple days in a row without getting any form of substantial exercise it seemed like I didn’t sleep as well. My sleep patterns after an especially big workout generally result in a deeper, less fitful sleep, but I wanted to see if there was any science to back up my experience.
Turns out there is. In one major study, researchers found that the time it took for kids to fall asleep was extended by an extra 3 minutes for each additional hour they were sedentary that day. The children who fell asleep quicker obviously slept longer, getting an extra 60 minutes of sleep, demonstrating a clear link between sleep onset latency and sleep duration in conjunction with physical activity. Another separate study, this time with adults, showed nearly identical results.
So there you have it. Sleep and weight loss are connected. Perhaps the first thing you do before you set off on a new diet or insane fitness regimen you should take the time to sit down and objectively evaluate your sleeping habits.
Falling asleep: the detriments of sleep latency. Ritchie Centre for Baby Health Research, Monash Institute of Medical Research, Monash University, Melbourne,
Effects of Exercise on Sleep. Department of Exercise Science, Norman J. Arnold School of Public Health, University of South Carolina, 1300 Wheat Street, Columbia, SC 29208, USA.