FoundationalConceptsNeuroscience

and emotional turmoil are commonly related to insomnia. Alcohol,
although a sedative-hypnotic, may lead to awakening and insomnia in
the middle of a night’s sleep, after its sleep-inducing effects wear off.
Treatment for insomnia best begins with addressing conditions
likely related to producing it as a symptom in the first place. One part
of this is optimizing conditions conducive to restful sleep. This is
called “sleep hygiene” and includes things like maintaining a regular
wake-sleep pattern, relaxing as much as possible before sleep, avoid-
ing exposure to bright light (such as computer screens) shortly before
retiring, avoiding eating large meals late in the evening, decreasing or
eliminating caffeine and alcohol consumption, and so forth.
Sleep apnea is a condition where the sleeper periodically stops
breathing or has abnormally shallow breathing. Sleep apnea is usually
caused by some kind of obstruction or constriction of the airway,
resulting in blocked airflow into the lungs. When this happens, the
sleeper wakes up from lack of air, breathing adjusts, and sleep returns.
However, if these brief awakenings happen repeatedly throughout the
night, it makes for a very disrupted sleep, often resulting in fatigue
and impaired performance the next day. Sleep apnea is thought to bea
fairly common condition, affecting upward of 5 percent of adults.
Narcolepsy has as its primary symptom excessive daytime
sleepiness, even after seemingly having a full night of sleep. Night-
time sleep cycling between NREM and REM stages is generally not
normal in narcoleptics. Genetic studies of narcolepsy in humans and
other animals have found associations with abnormalities related to
orexin, a neuropeptide involved in maintaining wakefulness. Orexin
derives its name from the Greek orexis, meaning appetite or desire—
reflecting its role in regulating feeding and other motivated behaviors.
Orexinergic neurons are located in the hypothalamus and send axons
widely throughout the brain—to the cerebral cortex and into the