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The word hypnagogia is sometimes used in a restricted sense to refer to the onset of sleep, and contrasted with hypnopompia, Frederic Myers's term for waking up. [2] However, hypnagogia is also regularly employed in a more general sense that covers both falling asleep and waking up.
A 2002 study of older adults (age 40–65) in San Diego found 3.1% had complaints of difficulty falling asleep at night and waking in the morning, but did not apply formal diagnostic criteria. [63] Actimetry readings showed only a small proportion of this sample had delays of sleep timing.
The first 8 hours are called the "advance zone" whereas the last few hours the "delay zone". The change from advancement to delay zones is progressive, passing through a long area of no effect (a "dead zone"), but the change from delay to advancement is abrupt, occurring a few hours before wake-up time or bedtime for light or melatonin ...
If you notice that you're waking up in the middle of the night, feeling exhausted in the middle of the day, or experiencing some other unpleasantness at the same time each day or night, consider ...
A circadian rhythm is an entrainable, endogenous, biological activity that has a period of roughly twenty-four hours. This internal time-keeping mechanism is centralized in the suprachiasmatic nucleus (SCN) of humans, and allows for the internal physiological mechanisms underlying sleep and alertness to become synchronized to external environmental cues, like the light-dark cycle. [4]
Sleep paralysis is a state, during waking up or falling asleep, in which a person is conscious but in a complete state of full-body paralysis. [1] [2] During an episode, the person may hallucinate (hear, feel, or see things that are not there), which often results in fear. [1] [3] Episodes generally last no more than a few minutes. [2]
A neurological condition or another medical problem may be suspected, in which case, blood tests, a CT scan or an MRI may be used. An overnight sleep study is usually not needed to detect this disorder, but may be indicated if other sleep disorders, such as sleep apnea and periodic limb movement disorder, seem likely.
Hypersomnia is a pathological state characterized by a lack of alertness during the waking episodes of the day. [3] It is not to be confused with fatigue, which is a normal physiological state. [4] Daytime sleepiness appears most commonly during situations where little interaction is needed. [5]