A new study by researchers at the University of Michigan shows that children who get less than 9 ¾ hours sleep in the third grade are 40 percent more likely to be fat in the sixth grade (whether they were already fat or not in the third grade).  It was found that the longer the kids slept, the less the chance for obesity.  It is already known that adults lacking sleep (less then 7 hours) are at increased risk for weight gain.  The researchers believe this problem is caused by disruption of healthy leptin function, as well as disruption of one of leptin’s companions, ghrelin (pronounced grel-an).

Leptin is involved in synchronizing hormone function in a variety of ways.  One example is leptin’s orchestration of insulin in response to a meal, wherein leptin produces a full signal and turns off insulin production by the pancreas.  This process malfunctions in a person with leptin resistance, in turn causing insulin resistance as well as a faulty full signal (a person has to eat too much to feel full). 

Another of leptin’s patterns is the 24 hour rhythm that synchronizes the timing of all hormone function during sleep (melatonin, growth hormone, thyroid hormone, testosterone, immune system repair activities, etc.).  In order to do this leptin levels are naturally highest around midnight, in terms of a 24-hour pattern.  When metabolism is working properly these higher levels of leptin not only naturally suppress appetite in the evening, they set the stage for a good night’s sleep and proper fat burning during sleep.  This process is disrupted by eating within three hours of bed.

When you go to sleep, assuming you haven’t eaten before bed, you are generally burning 60% of your calories from sugar and 40% from fatty acids.  About 6 – 7 hours following the completion of dinner, or about 2 – 3 hours into sleep, under the influence of leptin and glucagon, this ratio changes and you will now burn 40% of your calories from sugar and 60% from fatty acids – which continues until you wake up.  This process is orchestrated by your liver.  The longer you sleep the more fat you burn.  This means that sleep is a prime time for metabolic fat burning.

The reason children need to sleep longer than adults is because they are also growing their bodies, which requires additional time during sleep.  This new study is interesting as it shows that simply shorting sleep, in essence disrupting this leptin-controlled prime fat burning time, is sufficient to increase the risk for obesity.  This prime fat burning time is also disturbed by eating before bed, as the time in the 60% fat burning mode is either reduced or blocked entirely.

As a person gains weight around the midsection the liver also becomes clogged with fat.  This reduces the physical ability of the liver to burn fat properly during sleep.  This shows up as elevated blood sugar in the morning.  Morning fasting blood sugar should not be above 90, when it is it means the person could not get into fatty acid burning correctly during sleep and so the liver made sugar instead (or it means the person ate too much close to bed).  Of course, once the number rises too high a person is diabetic.  As a person eats according to the Five Rules of the Leptin Diet this problem of a clogged liver is gradually undone and the liver can potentially return to much more normal function, including nighttime fat burning.

The researchers also found that by disturbing leptin function, ghrelin levels were too high during the day.  Ghrelin is made in the stomach and acts as an appetite stimulant, especially for the intake of carbohydrates.  Healthy ghrelin function is absolutely vital for having a normal appetite as well as for the release of growth hormone.  However, when the hormone is too high during the day it leads to excess carbo ingestion, in turn fueling leptin resistance, insulin resistance, and weight gain.  This is easy to see – any time you short yourself on sleep you will notice you want more carbos the next day.

The moral of the story is do what you can to get a good night’s sleep and ensure your children are getting adequate sleep.  Children not only need sleep to maximize their genetic potential and growth, they need it to help maintain a healthy metabolism over the course of a lifetime.

Posted by Byron J. Richards at 07:20 PM.

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