Obesity and Sleep

There is increasing evidence of a strong relationship between a person’s weight and several potential sleep problems.  Scientists and sleep specialists are beginning to realize that healthy sleep may be critical for maintaining a healthy weight.

At least three important sleep problems have a connection to weight:

1. not getting enough sleep
2. obstructive sleep apnea
3. sleep-related eating disorder (or "night eating syndrome")

Beyond measuring weight in pounds or kilograms, a person’s tendency towards obesity is often described by a statistic called the "body mass index" or "BMI."  This calculation takes into account the relationship between a person’s height and weight.  The following BMI categories apply to adults.  A different means of interpreting the BMI is used for children.

For example, a 175-pound woman who is 5’ 3” tall has a BMI of 31.0 and falls into the "obese" category.  A man who is also 175 pounds, but is 6’ 2” tall, has a normal BMI of 22.5.

INSUFFICIENT SLEEP

Perhaps most impressive is evidence from multiple studies showing that the amount of sleep at night can have a strong relationship to weight.  Several studies have shown that people who sleep 7 to 8 hours a night tend to have the lowest BMIs.  People who sleep only 5 to 6 hours a night have a much greater tendency to have a significantly higher BMI.

Some studies have found relationships between the amount of sleep a person gets and levels of various hormones and other biochemical factors that regulate appetite.  Sleeping only 5 to 6 hours a night clearly seems to increase the risk for weight gain, as well as the risk of developing Type II diabetes, and short sleep times have been shown to adversely alter the levels of hormones that regulate appetite.  There may also be other risks associated with too little sleep such as a greater chance of developing cardiovascular disease and thyroid abnormalities.  Cortisol, a biochemical measure associated with stress of all kinds, is elevated in people not getting enough sleep.

Many people with weight concerns report that they notice reductions in their appetite and thus their ability to adhere to a good eating plan when they pay attention to getting enough sleep.  And at times, people with sleep disorders report that after their sleep problem is well treated, they find it easier to loose or maintain a good weight.

OBSTRUCTIVE SLEEP APNEA
It has been known for many years that obesity seems to increase the likelihood of developing sleep apnea.  More recent research points to the possibility that the reverse may also be true, that is, untreated sleep apnea may cause or contribute to weight gain.  Some overweight or obese people with sleep apnea find that after they are treated, they have some modest weight loss without any change in their diet.  Some notice that their waist circumference (a common measure of risk for diabetes and cardiovascular disease) gets smaller after starting on treatment for sleep apnea.  One research study using CAT scans to assess abdominal fat also showed this effect.

It appears very valuable for sleep apnea patients to get their sleep apnea under good control and to make every effort to get 7-8 hours of sleep per night.       

SLEEP-RELATED EATING DISORDER   and   NIGHT EATING SYNDROME

Sleep-related eating disorder usually involves a sleepwalking episode, outside of the patient’s awareness, that involves only eating.  Foods eaten are often highly fattening and sometimes not what the person would eat if awake.  Eating a lot of "junk food" (usually high in carbohydrates) or even uncooked foods would be common examples.  Severe weight gain can be a complication.

Night eating syndrome occurs when people are still awake.  People with this problem tend to eat little earlier in the day and become increasing ravenous after dinner, often eating the vast majority of their calories in the later evening, possibly delaying bedtime to keep eating.  These patients are often overweight or obese.

Both of these disorders are just beginning to be understood by sleep specialists and researchers.  Some successful treatments have been developed and a sleep disorders specialist with in depth training and experience with these disorders can often be helpful.

The science illuminating relationships between sleep and weight is young; however, it appears increasingly clear that ensuring sufficient sleep of adequate quality and treating any sleep disorders present may be important to achieving or maintaining a healthy weight.