Sleep apnea is a sleep disorder characterized by abnormal pauses in breathing during sleep. Each pause in breathing can last from a few seconds to a minute or more, and may occur up to 30 times an hour. Such pauses interrupt the supply of oxygen to the body, especially the brain. It is diagnosed with an overnight sleep test, called a sleep study.
An individual with sleep apnea is rarely aware of having difficulty breathing, even upon awakening. Sleep apnea is recognized as a problem by others witnessing the individual during episodes or is suspected because of its daytime symptoms and side effects. Symptoms may be present for years (or even decades) without identification, during which time the patient may get used to the daytime sleepiness and tiredness, which is the hallmark of the condition.
Sleep apnea’s many side effects are caused by lack of oxygen to the brain during sleep and include impaired ability of plan and initiates task, pay attention, memory, as well as moodiness, belligerence, and a decrease in everyday interests. Depression and fear of sleeping may occur. Snoring is common. It is sometimes called Pickwickian syndrome after the description of Joe, “the fat boy” in Dickens’s novel The Pickwick Papers.
People with sleep apnea are more likely to have obesity, hypertension, congestive heart failure, cancer, diabetes, metabolic syndrome, and generalized inflammation. The most common treatment is the use of a continuous positive airway pressure (CPAP) machine which keeps the patient’s airway open during sleep by means of a flow of pressurized air via a facial mask. However, many patients fail to use their CPAP machines on a nightly basis, especially in the long term, due to the uncomfortable nature of the facial mask during sleep.
Recently, a group in Turkey discovered that vitamin D levels are lower in people with sleep apnea than they are in controls. The controls were people suspected of having sleep apnea but who did not have it on the sleep study. The average levels were significantly different in patients than controls (17 versus 20 ng/ml), and there was a trend for deficiency to parallel the severity of OSA. They also found that diabetes in sleep apnea was more likely in those with the lowest levels of vitamin D.
More recently, a group in Spain discovered that in a large group of patients with sleep apnea, vitamin D levels were inversely associated with diabetes and the metabolic syndrome. The mean vitamin D levels of the sleep apnea patients in Spain were considerably higher than those in Turkey.
Around the same time that the Turkish group published their data, a Brazilian group discovered that sleep apnea is seasonal with the lowest incidence in the summer and the highest in the winter.
As obesity is one of the main causes of sleep apnea, the possibility remains that the correlation between vitamin D levels and sleep apnea is just a result of obesity. Given this, the probability is that there will be no treatment effect with vitamin D. However, it may help reduce the illnesses associated with sleep apnea, such as hypertension, congestive heart failure, cancer, metabolic syndrome, and generalized inflammation.
Remember as well, all the above epidemiological studies were really studies of UV light exposure, not vitamin D supplements. As I have said before, the most conservative and scientific approach is to raise your vitamin D levels by both supplementation and UV radiation, which means sunshine in the summer and low pressure sun beds in the winter.