The most common sleep disorder is insomnia.[2] Others are sleep apnea, narcolepsy and hypersomnia (excessive sleepiness at inappropriate times), sleeping sickness (disruption of sleep cycle due to infection), sleepwalking, and night terrors. Management of sleep disturbances that are secondary to mental, medical, or substance abuse disorders should focus on the underlying conditions.
^ Jump up to: a b c d e f g h i j k l m n o p q r s t u Walker, Matthew P.; Jagust, William J.; Winer, Joseph R.; Mander, Bryce A. (2016-08-01). "Sleep: A Novel Mechanistic Pathway, Biomarker, and Treatment Target in the Pathology of Alzheimer's Disease?". Trends in Neurosciences. 39 (8): 552–566. doi:10.1016/j.tins.2016.05.002. ISSN 0166-2236. PMID 27325209.
At the same time, it has been shown that memory consolidation in long-term memory (which depends on the hippocampus) occurs during NREM sleep.[29][33] This indicates that a decrease in the NREM sleep will result in less consolidation and therefore poorer memory performances in hippocampal-dependent long-term memory.[29][33] This drop in performance is one of the central symptoms of AD.[29]  
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%).[67]
Sort of a milder cousin of sleep apnea, UARS occurs when some type of resistance slows or blocks air in the nasal passages. The most common causes are mild nasal congestion or a tongue position during sleep that blocks breathing. Because the resistance makes it harder work simply to breathe, your body is half-waking up over and over again during the night, so you don't feel refreshed in the morning.
Neurodegenerative diseases have been often associated with sleep disorders, mainly when they are characterized by abnormal accumulation of alpha-synuclein, such as multiple system atrophy (MSA), Parkinson's disease (PD) and Lewy body disease (LBD).[21][22][23][24][25][26][27] For instance, people diagnosed with PD have often presented different kinds of sleep concerns, commonly regard to insomnia (around 70% of the PD population), hypersomnia (more than 50% of the PD population), and REM sleep behavior disorder (RBD) - that may affect around 40% of the PD population and it is associated with increased motor symptoms.[21][22][23][24][25][27] Importantly, RBD has been also highlighted as a strong precursor of developing dementia in PD patients over several years in prior, which seems to be a great opportunity for improving the treatments of the disease.[22][24]
This clock is a small part of the brain called the suprachiasmatic nucleus of the hypothalamus. It sits just above the nerves leaving the back of our eyes. Light and exercise "reset" the clock and can move it forward or backward. Abnormalities related to this clock are called circadian rhythm disorders ("circa" means "about," and "dies" means "day").

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.
Narcolepsy is characterized by “sleep attacks” that occur during the day. This means that you will suddenly feel extremely tired and fall asleep without warning. The disorder can also cause sleep paralysis, which may make you physically unable to move right after waking up. Although narcolepsy may occur on its own, it is also associated with certain neurological disorders, such as multiple sclerosis.
What to do: See your dentist for an exam. Bite problems are often a cause of bruxism, and it's a good idea to check for damage to your teeth. It's likely she'll suggest lifestyle changes, such as cutting out alcohol before bed. If you chew gum, stop -- the habitual chewing action can make it more likely you'll grind your teeth at night. Wearing a dental guard or splint at night is usually the next step for bruxism. Your dentist will fit you with a device that prevents your jaw from clenching. Other treatments include Botox injections to the jaw muscle, and a biofeedback device called Grindcare.