Sleep Disorders: serious disorders in the normal sleep pattern that interfere with daytime functioning and cause subjective distress. (Hockenbury, 139) There are a number of sleep disorders that range from trouble falling asleep, to nightmares, sleepwalking, and sleep apnea (problems with breathing that cause loud snoring). Poor sleep may also be caused by diseases such as heart disease, lung disease, or nerve disorders. (NCIt)

“Consciousness” takes us beyond an unconscious awareness of our body, and thereby allows us to attend to the world and react to it in what is known as ‘context-dependent’ ways. For example, if you’re sleepwalking, you can walk around; but since you’re unconscious, you can’t respond to your surroundings—which would be the “context.” And, of course, sleepwalking can be dangerous. (Campbell, BSP71) The need to reduce “cognitive dissonance” after a “decision” is very powerful, and it pretty much happens unconsciously. One way we know this is from the discomfort we feel when we can’t reduce dissonance—when we have those sleepless nights, when we beat ourselves up with regret for the road not taken, and so forth. Mostly, most of us, though, are pretty good at justifying the decision we make, the choice we made, and getting a good night’s sleep. (Tavris, BSP77BI) (According to) the “opponent process theory,”  there are two forces that are locked in a—I’ll call it a 'death match'—in your life. One we call the “homeostatic sleep drive.” This is the drive to put you to sleep, and the sum total of tissues and molecular forces in your body wants to put you to sleep. And it’s at war all day and all night with your other drive, which we call the “circadian arousal system.” The circadian arousal system is the one that wants to keep you awake all the time. If you deregulate those you can begin to accumulate a sleep debt, because they’re supposed to be held in a fine balance. (Medina, BSP37)

Familial Advanced Sleep Phase Syndrome: associated with disruption of the normal 24 hour sleep wake cycle secondary to travel, shift work, or other causes. (MeSH) Affected individuals promptly fall asleep at 7:30 each night and awaken suddenly at 4:30 A.M., thanks to a "mutation" in a gene on chromosome 2 called 'period.' (Lewis, 153)

Insomnia: disorders characterized by impairment of the ability to initiate or maintain sleep. This may occur as a primary disorder or in association with another medical or psychiatric condition. (MeSH) Trouble falling asleep or staying asleep through the night. Episodes may come and go, last up to 3 weeks (short-term), or be long-lasting (“chronic”). Sleep habits we learned as children may affect our sleep behaviors as adults. When we repeat these behaviors over many years, they become habits. (PubMedHealth2) People repeatedly complain about the quality or duration of their sleep, have difficulty going to sleep or staying asleep, or wake before it is time to get up. (Hockenbury, 140) 'Clock' genes and at least three other genes are associated with insomnia. (Lewis, 153)

Narcolepsy: a nervous system problem that causes extreme sleepiness and attacks of daytime sleep. Many people with narcolepsy have low levels of ‘hypocretin’ (also known as ‘orexin’). This is a chemical made in the brain that helps you stay awake. In some people with narcolepsy, there are fewer of the cells that make this chemical. This may be due to an “autoimmune reaction.” An auto immune reaction is when the body’s immune system mistakenly attacks healthy tissue. Narcolepsy can run in families. Researchers have found certain genes linked to narcolepsy. (PubMedHealth2) A single gene causes narcolepsy in dogs and humans. The 'hypocretin/orexin' receptor gene is on "chromosome" 6. The brains of humans with narcolepsy and "cataplexy" are remarkably deficient in hypocretin/orexin, but it isn't the orexin gene that causes the condition in humans - it is likely another gene that controls it. (Lewis, 153) A person with narcolepsy falls asleep suddenly several times a day. Rarely inherited as a single-gene trait. More often "polygenic" requiring an environmental trigger. (Lewis, 152)

Cataplexy: a condition characterized by transient weakness or paralysis of (muscles) triggered by an emotional stimulus or physical exertion. (MeSH) During these attacks, you can't control your muscles and can't move. Strong emotions, such as laughter or anger, can trigger cataplexy. Attacks often last from 30 seconds to 2 minutes. You remain aware during the attack. In severe cases, you may fall and stay paralyzed for as long as several minutes. (PubMedHealth2) Short and sudden episodes of "muscle" weakness. The jaw sags, the head drops, knees buckle and the person falls to the ground. Often occurs during a bout of laughter or excitement. (Lewis, 152) 

Night Terrors: typically occur during stage 3 or 4 of 'N-REM sleep' in the first few hours of sleep. Much more intense than a run-of-the-mill nightmare. Sharply increased physiological arousal - restlessness, sweating and a racing heart. Tend to be brief, usually lasting only a matter of seconds. Not regarded as a true sleep disorder or psychological problem unless they occur frequently. (Hockenbury, 141)

Sleep Apnea: a condition in which the flow of air pauses or decreases during breathing while you are asleep because the airway has become narrowed, blocked, or floppy. A pause in breathing is called an ‘apnea episode.’ A decrease in airflow during breathing is called a ‘hypopnea episode.’ Almost everyone has brief apnea episodes while they sleep. In ‘central sleep apnea’ breathing stops over and over during sleep. (PubMedHealth2) A sleep disorder that is marked by pauses in breathing of 10 seconds or more during sleep, and causes unrestful sleep. Symptoms include loud or abnormal snoring, daytime sleepiness, irritability, and depression. (NCIt) Disorders characterized by multiple cessations of “respirations” during sleep that induce partial “arousals” and interfere with the maintenance of sleep. (MeSH)

Sleep Paralysis: the inability to move for a few minutes after awakening. (Lewis, 152) This is when you can't move your body as you start falling asleep or when you first wake up. It may last up to 15 minutes. (PubMedHealth2)

Sleeping Sickness: an infection with germs carried by certain flies. It results in swelling of the brain. When an infected fly bites you, the infection spreads through your blood. The disease does not occur in the United States. But travelers who have visited or lived in Africa can have the infection. (PubMedHealth2) Transmitted to humans and livestock by ‘tsetse flies’ in equatorial Africa as well as in parts of South America and Asia. Nearly half a million people become infected with sleeping sickness each year, and the disease is fatal if untreated. (Brooker, 598)