Obstructive sleep apnea (OSA), the intermittent cessation of breathing during sleep, occurs when the upper airway tissues (e.g., tonsils, fatty tissue) repeatedly collapse into the upper airway and partially or fully block airflow. The collapsibility of the upper airway in people with OSA is believed to occur because the upper airway muscles relax excessively during sleep, which allows structures supported by the muscles to collapse into the upper airway. Some research indicates that altered neuronal activation may contribute to the reduced tone of the upper airway muscles. Much of this research has focused on innervation of dilator muscles such as the genioglossus muscle (which forms the bulk of the tongue). However, another structure that contributes to obstruction is the soft palate. In recent years, scientists have begun examining whether neuronal injury in the soft palate muscles could contribute to OSA.
Restless legs syndrome (RLS) affects an estimated 7–10 percent of the general population. The prevalence of RLS is greater in patients with diabetes than in people without diabetes. Diabetic neuropathy (i.e., pathological changes in the peripheral nerves) has been implicated as a risk factor for RLS in diabetic patients. To what extent and how diabetic neuropathy contributes to RLS is unclear. Recent investigations into the relationship between RLS and diabetes have revealed some interesting findings.
The prevalence of certain sleep disorders such as obstructive sleep apnea, insomnia and restless legs syndrome are increased among children and adults with attention deficit hyperactivity disorder (ADHD).
The neurocognitive disorder Alzheimer’s disease affects an estimated 5 million Americans. Its prevalence is expected to triple by 2060. People affected by Alzheimer’s disease have increasing problems with memory, judgement and doing daily tasks of living as the disease progresses. Various studies have indicated that obstructive sleep apnea (OSA) is associated with an increased risk of developing Alzheimer’s disease and that people with OSA have increased levels of certain biomarkers (e.g., amyloid beta protein) associated with Alzheimer’s disease. Scientists have recently noted increased levels of biomarkers associated with Alzheimer’s disease in young children with OSA.
An overlooked symptom in people with obstructive sleep apnea (OSA) is olfactory dysfunction (i.e., impairment in the sense of smell) such as an inability to detect or distinguish between odors. A finding that the sense of smell improves soon after a person with OSA begins continuous positive airway pressure (CPAP) treatment corroborates a possible link between olfactory dysfunction and OSA.
The advent of actigraphy in the 1990s made it possible to indirectly record a person’s sleep-wake cycles based on the person’s activity level, with increased activity indicating wakefulness and decreased activity indicating sleep. In actigraphy, a device — an actigraph — which is typically worn on the wrist, continually records movement data over a prolonged time — one week or more.