Thursday, May 31, 2012

Are your sleep habits making you fat?

We all know how important sleep is, especially when we don't get enough. I am willing to bet, however, that the majority of us don't actually realize all that's at risk when we don't get enough of it.
Everything from our energy through the day, our mood, and even our weight loss can be negatively effected from lack of sleep. Much like food, getting too much, or too little sleep can be extremely detrimental to our overall health.
How mush sleep do we actually need each night in order to function properly? Studies have been done suggesting that the minimum is 7 hours, but that it's better to get between 8-10 hours per night!  I don't know if I have ever managed to get 10 hours of sleep (in one night) in my adult life! Lucky for me taking an afternoon nap (legitimate sleep, not just watching a movie while relaxing) can count as those extra hour(s) that I missed out on during the night.

What's the big deal with sleep, and body weight anyway?

A study conducted in 2005 on 10,000  adults, suggested that the United States obesity epidemic might, in part, be caused by a corresponding decrease in the average number of sleep hours. This study found that people between the ages of 32 and 49 who sleep fewer than 7 hours each night are significantly more likely to be obese.  Also, staying awake beyond midnight seemed to increase the likelihood of obesity.  These associations have a “dose-response” relationship, with later bedtimes and shorter sleeping hours resulting in greater levels of body fat gain.  Wake-up time was not significantly related to obesity.  Similarly, a study that followed the growth of more than 9,000 children from birth onwards showed that children who slept the least when they were 30 months old were more likely to be obese at age 7 than children who slept more.

While there are many reasons that lack of sleep could influence body fat, one of them may be the decreased growth hormone (GH), thyroid stimulating hormone (TSH), and increased cortisol, most notably in the evening.  Moreover, chronic sleep restriction results in elevated sympathetic nerve activity and a slow insulin response.  This is the perfect storm of peripheral effects to accentuate obesity:
  • Lowered glucose tolerance (GT)
  • Increased sympathovagal balance
  • Increased evening and nocturnal cortisol levels
  • Lowered leptin
  • Insufficient thyroid stimulating hormone (TSH)
Pragmatically speaking, lack of sleep may lead to more body fat simply because more time spent not sleeping means more time to eat. And those junk food commercials start looking pretty appealing at 1 a.m.

So, less sleep potentially results in more body fat, big deal.  Well, that’s not it.  Getting less than 7.5 hours of sleep each night also means that you’re at greater risk of heart attack, stroke, and sudden cardiac death than your pals who get plenty of snooze time.  Also, with the weight gain that could come with minimal sleep, you’d likely see insulin resistance (IR), glucose intolerance and type 2 diabetes.
Check this out: Eleven healthy men in their 20s were only allowed 4 hours of sleep for six straight nights. At the end of this, the young men had the insulin sensitivity of a 70 year old pre-diabetic! Despite the small sample size in this study, the results are suggestive.

A few interesting facts about sleep:

*Sleep debt is cumulative, meaning the more nights you go with less sleep the greater likelihood of negative effects taking place.  Experts hypothesize that each hour of sleep debt needs to be repaid, eventually.

*High concentrations of cortisol –- a stress hormone -– can negatively affect sleep quality.  This is a double edged sword, as poor sleep can effect the concentration on cortisol in your body.

*Sleep may improve memory formation and recall

*Knowing you’ll get to nap during the day can help to lower blood pressure. Maybe this is why we were all so happy in pre-school.

Make good sleep a priority, just like the rest of your healthy habits. Here are several factors to consider when generating a sleeping pattern:
  • Consistency:  Keep a relatively consistent bedtime and wake time. Staying up late and sleeping in on weekends can disrupt your routine during the week.
  • Light: Keep the bedroom extremely dark, to tell the body’s light-sensitive clock that it’s time to sleep.
  • Noise: Keep the bedroom extremely quiet or use a white noise generator (such as a fan).
  • Relaxation/routine: Develop a pre-bed routine that is relaxing and familiar.  Television, work, computer use, movies and deep/stressful discussions late at night can disrupt sleep.
  • Temperature: Keep a slightly cool temperature in the room, between 66-72 F or 18-22 C.
  • Stimulants: Eliminate stimulants like caffeine/nicotine, especially later in the day.
  • Exercise: It’s not only good for a tight butt and big guns, it can help improve sleep.
  • Fullness: Eating a dinner that makes you overly full can disturb sleep.

Source: Precision Nutrition


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