Sleep

Getting “enough” sleep is a fundamental requirement of human function. It is also not just the number of hours of sleep, but the quality of that sleep, that ensures overall restfulness, relaxation and restoration, and the proper functioning of the circulatory, digestive, endocrine, immune and nervous systems. Sleep is defined as “a biobehavioral phenomenon that is regulated by circadian, homeostatic, and neurohormonal processes.”

Since sleep is such an essential “recurring state” for human physiology, it is no surprise that abnormal, inconsistent or deprived sleeping patterns can result in a range of health consequences and disease. Type 2 diabetes is no exception, and having problems with sleeping is rightly considered a major risk factor for developing type 2 diabetes.

A substantial amount of research has connected sleep deprivation, meaning short sleep duration, to the incidence of type 2 diabetes. While the specific number may vary depending on the particular study, it is generally considered that getting less than 5 hours of sleep per night, regardless of the quality of the sleep, greatly increases one’s risk of developing type 2 diabetes.

There are several possible reasons for why insufficient sleep increases the likelihood of developing metabolic conditions such as insulin resistance, prediabetes and type 2 diabetes. Some of these potential causes are direct biological mechanisms connected to insufficient sleep, and others are related to socioeconomic and lifestyle risk factors that tend to have negative effects on sleeping patterns and can be considered more indirect, but no less important. The later include poor dietary choices and inactivity, as well as irregular and sometimes excessive working hours, especially for “shift-workers,” which can not only limit overall sleep but change circadian rhythms and metabolism within the body due to irregularity in the timing of sleep. Also stress, anxiety and depression are closely linked to sleep deprivation and disorders like insomnia, and themselves are strong independent risk factors for developing type 2 diabetes.

There are many biological factors at play when one does not get enough sleep.  Included are changes in the function of the neuroendocrine system, of which the insulin-producing beta cells of the pancreas are a part, and negative effects on glucose regulation when one is deprived of “slow-wave sleep”(deep sleep, as opposed to REM[rapid-eye-movement] sleep). Several studies have demonstrated that insufficient sleep can lead to both glucose intolerance and insulin resistance, which are two major risk factors themselves in the eventual development of type 2 diabetes. This occurs due to mechanisms for glucose production, storage and absorption that are disrupted when sleep is restricted. If these conditions persist, whether solely due to lack of sleep or a combination of risk factors, type 2 diabetes often results. Lack of sleep also has been shown to increase inflammation, which raises blood pressure and can result in hypertension, which is known to increase the risk of developing both type 2 diabetes and cardiovascular disease(CVD).

What has been more difficult to confirm in studies is the optimal amount of sleep in regards to diabetes prevention. General health guidelines normally recommend getting 7-9 hours of sleep for adults (age 18-64), with slightly more sleep recommended for teenagers and substantially more sleep recommended for younger children.

What research has been showing with type 2 diabetes risk, however, is that too much sleep can also increase the chances of developing the disease. The physiological pathways to explain this interesting conclusion are less clear than those related to sleep deprivation, and may be more of a consequence instead of an independent cause, but the results are clear: sleeping both too little and too much increases type 2 diabetes risk.

For people with obstructive sleep apnea(OSA), for example, which describes prolonged pauses in breathing during sleep, often there is a need for more hours of sleep to feel rested, and OSA itself has been shown as an independent risk factor for both insulin resistance and type 2 diabetes. People with OSA are also much more likely to be obese, with obesity itself being perhaps the single most important risk factor for developing type 2 diabetes, as well as heart and cardiovascular disease. Narcolepsy, another sleeping disorder, which is characterized by uncontrollable sleepiness, has also been independently connected to increased type 2 diabetes incidence.

With due consideration to current trends and research, the optimal amount of sleep for maintaining overall health and also for preventing type 2 diabetes appears to be 7-8 hours, with those sleeping less than 5 hours and more than 9 hours being at the highest risk for developing this highly preventable disease.

For those with trouble sleeping, and especially those that are already at high risk for developing type 2 diabetes, it is imperative to practice techniques to improve “sleep hygiene” in order to get a consistently good night’s rest. These include exercising daily, eating a healthful and balanced diet(while not eating too much in the nighttime before sleep), having a healthy and active sex life and practicing mindfulness exercises that aid in relaxation, such as breathing, meditation and reading.

Resources and Further Reading:

A comprehensive meta-analysis study of sleep as a risk factor for type 2 diabetes, concluding that both too little and too much sleep increases risk: 
http://care.diabetesjournals.org/content/38/3/529.long

One of many studies that clearly connected insufficient sleep to type 2 diabetes: 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2276127/

Obstructive Sleep Apnea as a risk factor for Type 2 diabetes: 
https://www.ncbi.nlm.nih.gov/pubmed/22988888?access_num=22988888&link_type=MED&dopt=Abstract

Narcolepsy connected to increased type 2 diabetes incidence: 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3250362/

Recommended sleeping guidelines for the general populace: 
http://www.sleephealthjournal.org/article/S2352-7218(15)00015-7/fulltext

Some recommendations for better sleep hygiene: 
http://healthysleep.med.harvard.edu/healthy/getting/overcoming/tips

Some more specific techniques for getting quality sleep: 
https://www.huffingtonpost.com/2014/05/04/relaxation-sleep-tips_n_5240448.html

Sleep and Obesity: 
https://www.hsph.harvard.edu/obesity-prevention-source/obesity-causes/sleep-and-obesity/

Sex helps sleep, and sleep helps sex: 
https://edition.cnn.com/2017/06/01/health/sex-sleep-kerner/index.html

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