alt=A<unk> ing girl<unk>  is a naturally recurring state of mind and body, characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and inhibition of nearly all voluntary muscles during rapid eye movement (REM)<unk> , and reduced interactions with surroundings. It is distinguished from wakefulness by a decreased ability to react to stimuli, but more reactive than a coma or disorders of consciousness, with<unk>  displaying different, active brain patterns.<unk>  occurs in repeating periods, in which the body alternates between two distinct modes: REM<unk>  and non-REM<unk> . Although REM stands for "rapid eye movement", this mode of<unk>  has many other aspects, including virtual paralysis of the body. A well-known feature of<unk>  is the dream, an experience typically recounted in narrative form, which resembles waking life while in progress, but which usually can later be distinguished as fantasy. During<unk> , most of the body's systems are in an anabolic state, helping to restore the immune, nervous, skeletal, and muscular systems; these are vital processes that maintain mood, memory, and cognitive function, and play a large role in the function of the endocrine and immune systems. The internal circadian clock promotes<unk>  daily at night. The diverse purposes and mechanisms of<unk>  are the subject of substantial ongoing research.<unk>  is a highly conserved behavior across animal evolution. Humans may suffer from various<unk>  disorders, including dyssomnias such as insomnia, hypersomnia, narcolepsy, and<unk>  apnea; parasomnias such as<unk> walking and rapid eye movement<unk>  behavior disorder; bruxism; and circadian rhythm<unk>  disorders. The use of artificial light has substantially altered humanity's<unk>  patterns. Common sources of artificial light include the screens of electronic devices such as smartphones and televisions, which emit large amounts of blue light, a form of light typically associated with daytime. This disrupts the release of the hormone melatonin needed to regulate the<unk> -cycle.
Sleep
Nightmare
Twilight sleep
Nightscout
Yawn
Conscious breathing
Window period
Morning care