Over time, sleeping five hours or less or nine hours or more each night may increase your risk of developing diabetes.
After following more than 70,000 diabetes-free women for a 10-year period, researchers found that women who slept five hours or less every night were 34 percent more likely to develop diabetes symptoms than women who slept for seven or eight hours each night.
Comparatively, women who slept nine hours or more each night were 35 percent more likely to develop diabetes symptoms.
During the course of the study, which began in 1986, 1,969 women developed diabetes and most showed symptoms of the condition.
Researchers were not certain why sleeping too much or too little might be linked to diabetes, though one theory involves leptin, a hormone that may play a role in signaling the body to stop eating.
Too little sleep may reduce levels of leptin, possibly causing people to gain weight and develop diabetes. When researchers removed factors such as overweight and obesity, too little sleep was not linked to diabetes, which suggests that sleep may indirectly affect diabetes by promoting weight gain.
One theory why too much sleep may increase diabetes risk is that people who sleep a lot tend to have poorer health in general. They may also have sleep apnea, a condition that may prevent restful sleep and cause people to sleep more overall due to feeling tired. Independently, sleep apnea may also increase diabetes risk.
Diabetes Care February, 2003;26:380-4
As I said two years ago:
In this country we have an epidemic of people who are not sleeping enough. The average American is only getting seven hours of sleep, and I am afraid I fall right in with the average in this department.
Prior to the invention of the electric light bulb, which has allowed us to transform night into day, people were sleeping NINE hours per night. While there are many benefits of electric light, constantly neglecting our sleeping needs poses a huge risk to our health.
If you are interested in finding more information on this fascinating subject you can look into Lights Out: Sleep, Sugar, and Survival by T. S. Wiley and Bent Formby. Nearly one-third of the book is references to peer-reviewed literature, so it is very carefully documented.
The authors believe that it is light, not what we eat or whether we exercise, that causes obesity--and diabetes, heart disease and cancer.