Delayed sleep phase disorder (DSPD), inability to awaken and fall asleep at socially acceptable times but no problem with sleep maintenance, a disorder of circadian rhythms. Other such disorders are advanced sleep phase disorder (ASPD), non-24-hour sleep–wake disorder (non-24) in the sighted or in the blind, and irregular sleep wake rhythm, all much less common than DSPD, as well as the situational shift work sleep disorder.
Primary sleep disorders are most common in men and women over the age of 65. About half of the people claim to have some sleep problem at one point. It is most common in the elderly because of multiple factors. Factors include increased medication use, age-related changes in circadian rhythms, environmental and lifestyle changes  and pre diagnosed physiological problems and stress. The risk of developing sleep disorders in the elderly is especially increased for sleep disordered breathing, periodic limb movements, lestless legs syndrome, REM sleep behavior disorders, insomnia and circadian rhythm disturbances.
Obstructive sleep apnea (OSA) affects around 4% of men and 2% of women in the United States. In general, this disorder is more prevalent among men. However, this difference tends to diminish with age. Women experience the highest risk for OSA during pregnancy. Also, they tend to report experiencing depression and insomnia in conjunction with obstructive sleep apnea. In a meta-analysis of the various Asian countries, India and China present the highest prevalence of the disorder. Specifically, about 13.7% of the Indian population and 7% of Hong-Kong's population is estimated to have OSA. The two groups experience daytime OSA symptoms such as difficulties concentrating, mood swings, or high blood pressure, at similar rates (prevalence of 3.5% and 3.57%, respectively).
What to do: Ask your doctor if your restless leg syndrome might be caused by another health condition or by a medication you're taking. Diabetes, arthritis, peripheral neuropathy, anemia, vitamin B deficiency, thyroid disease, and kidney problems can all contribute to restless leg syndrome. Medications that can cause restless leg syndrome as a side effect include antidepressants, antihistamines, and lithium. Treating the underlying condition or changing medications may banish the symptoms. Restless leg syndrome has been linked to deficiencies in iron and B vitamins, particularly folate, so talk to your doctor about boosting your intake of these nutrients.
What to do: See a doctor, who will likely first check you for underlying conditions related to PLMD. Diabetes, thyroid disorders, anemia, and a number of other conditions can cause PLMD. If you do have another condition, the doctor will treat it and see if the PLMD goes away. The next step is to control the involuntary movements with medication. Drugs that suppress muscle contractions work well for preventing PLMD. The doctor may also prescribe medication to help you sleep more deeply, with the idea of preventing the involuntary movements from keeping you in light sleep.
Sleep apnea is a common (and treatable) sleep disorder in which your breathing temporarily stops during sleep, awakening you frequently. If you have sleep apnea you may not remember these awakenings, but you’ll likely feel exhausted during the day, irritable and depressed, or see a decrease in your productivity. Sleep apnea is a serious and potentially life-threatening sleep disorder, so see a doctor right away and learn how to help yourself.
Recent studies have also linked sleep disturbances, neurogenesis and AD. Indeed, it is now known that neurogenesis exists and that the subgranular zone and the subventricular zone keep on creating new neurons even in an adult brain. These new cells are then incorporated into neuronal circuits and interestingly, the supragranular zone is found in the hippocampus. These new cells will contribute to learning and memory and will play a role in the hippocampal-dependent memory.
A systematic review states 7.6% of the general population experiences sleep paralysis at least once in their lifetime. Its prevalence among men is 15.9% while 18.9% of women experience it. When considering specific populations, 28.3% of students and 31.9% of psychiatric patients have experienced this phenomenon at least once in their lifetime. Of those psychiatric patients, 34.6% have panic disorder. Sleep paralysis in students is slightly more prevalent for those of Asian descent (39.9%) than other ethnicities (Hispanic: 34.5%, African descent: 31.4%, Caucasian 30.8%).
Keep a pen and paper next to your bed. If you're often kept awake by racing thoughts and worries and you tend to make to-do lists in your head, keep a pen or pencil and a small pad of paper handy and write them down. As you put each item down on paper, imagine yourself setting aside that concern. (Again, use a book light; don't turn on the overhead or a bright bedside light to write.)