Getting Enough Sleep Keeps You from being Too Sweet

January 09, 2009

Getting Enough Sleep Keeps You from being Too Sweet 

 Competency # 7 Sleep                      Reference: Science News 2009 Jan 3;Vol 175 # 1 by Laura Sanders and Nature Genetics 2008 Dec; 41, 77-81 I. Prokopenko et al 

 Get just 5 hours of sleep for three days in a row (instead of 8) and normal healthy people start to have their blood sugar rise as they become insulin resistant.  We’ve reported on that in the past.  In addition, sleep-deprived people start choosing sweet, sugary foods over other foods.   Go back to 8 hours of sleep a night and you are back to normal insulin sensitivity in just a couple of days. 

 Isn’t that interesting!  You can make yourself diabetic just by missing sleep for a couple of days.  How does that work? Well, now we know.  It turns out there is a receptor protein on the outside of cells that binds melatonin and sets off sleep-wake changes that occur inside of cells.  Scientists have already shown that depression, obesity, and even sudden death all correlate with lack of sleep, so we know that not getting enough sleep is doing something bad to our bodies.  And our bodies are essentially the sum of billions of cells and their individual metabolic needs.  

It’s melatonin that’s the key.  Melatonin is the hormone that your internal clock puts out each day through the pineal gland.  It rises at night, helping put you to sleep.  It falls during the day when you are awake and alert.  Your internal clock is pretty accurate, as you well know.  Many of us don’t have to set our alarms because we just wake up within a few minutes of our alarm, shutting it off so that our partner can snooze for a few more minutes.  When it gets dark, melatonin goes up.  You get sleepy. There is a gene called MTNR1B that codes the melatonin receptor on cells.  

When that gene has a single codon change in its DNA with a G instead of a C, a slightly different melatonin receptor protein results.  This changed receptor protein is strongly linked to obesity and a stronger risk for diabetes.  Insulin-producing cells in the pancreas also have that melatonin receptor.  If you add melatonin to beta cells that are in a petri dish, those cells make less insulin.  Hence, a lousy receptor and you end up with less feedback to the pancreas causing insulin levels to rise.  Insulin is your storage hormone meant to help you store extra calories.  With higher insulin levels, you put on weight.  Oops.  Get enough sleep and you become more insulin sensitive. This is the story that’s unfolding.  We are learning our genes.  The human genome project will unpack more and more “gene stories” and soon enough we will be able to read your risk profile for various illnesses by testing your DNA profile.    MTNR1B.  I could have told you that.  When I work nights, I have to have sugar all night long. 

 WWW: What will work for me.  This study confirms for me the need to be in bed for at least 7 hours.  As I age, my sleep is becoming more fragile.  It’s easier to wake up after just 5 hours.   I’m practicing mental exercises that put my brain back down to rest.  We’ll go over some of those exercises in a week or two.  Sweet, sweet sleep.   Get enough, and you won’t be quite so sweet.

This column written by Dr. John E Whitcomb, MD, Brookfield Longevity, Brookfield, WI (262-784-5300)