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It has long been believed that alpha waves indicate a wakeful period during sleep. [citation needed] This has been attributed to studies where subjects report non-refreshing sleep and have EEG records reporting high levels of alpha intrusion into sleep. This occurrence is known as alpha wave intrusion. [25]
Alpha, beta, theta, gamma, and delta waves are all seen in the different stages of sleep. Each waveform maintains a different frequency and amplitude. Alpha waves are seen when a person is in a resting state, but is still fully conscious.
Stage 3 – previously divided into stages 3 and 4, is deep sleep, slow-wave sleep (SWS). Stage 3 was formerly the transition between stage 2 and stage 4 where delta waves, associated with "deep" sleep, began to occur, while delta waves dominated in stage 4.
Such experiences are associated especially with stage 1 of NREM sleep, [28] but may also occur with pre-sleep alpha waves. [29] [30] Davis et al. found short flashes of dreamlike imagery at the onset of sleep to correlate with drop-offs in alpha EEG activity. [31]
Sleep onset is the transition from wakefulness into sleep. ... as well as alpha wave activity (smooth electrical activity of 8–12 Hz recorded from the brain ...
Known as slow-wave sleep or stage 3 non-REM sleep, this is the deepest stage of sleep and the hardest to wake up from. Brain activity slows down, muscles and bones strengthen, hormones regulate ...
During slow wave sleep, the cortex generates brief periods of activity and inactivity at 0.5–4 Hz, resulting in the generation of the delta waves of slow wave sleep. During this period, the thalamus stops relaying sensory information to the brain, however it continues to produce signals, such as spindle waves, that are sent to its cortical ...
A hypnic jerk, hypnagogic jerk, sleep start, sleep twitch, myoclonic jerk, or night start is a brief and sudden involuntary contraction of the muscles of the body which occurs when a person is beginning to fall asleep, often causing the person to jump and awaken suddenly for a moment.