Wakefulness in the context of "Coma"

The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep. It is sometimes called the ultradian sleep cycle, sleep–dream cycle, or REM-NREM cycle, to distinguish it from the circadian alternation between sleep and wakefulness. In humans, this cycle takes 70 to 110 minutes (90 ± 20 minutes). Within the sleep of adults and infants there are cyclic fluctuations between quiet and active sleep. These fluctuations may persist during wakefulness as rest-activity cycles but are less easily discerned.

Hypnagogia is the transitional state from wakefulness to sleep, also defined as the waning state of consciousness during the onset of sleep. Its corresponding state is hypnopompia – sleep to wakefulness. Mental phenomena that may occur during this "threshold consciousness" include hallucinations, lucid dreaming, and sleep paralysis.

Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with the surrounding environment. While sleep differs from wakefulness in terms of the ability to react to stimuli, it still involves active brain patterns, making it more reactive than a coma or disorders of consciousness.

Sleep occurs in repeating periods, during which the body alternates between two distinct modes: rapid eye movement sleep (REM) and non-REM sleep. Although REM stands for "rapid eye movement", this mode of sleep has many other aspects, including virtual paralysis of the body. Dreams are a succession of images, ideas, emotions, and sensations that usually occur involuntarily in the mind during certain stages of sleep.

Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class and is the most commonly consumed psychoactive substance globally. It is mainly used for its eugeroic (wakefulness promoting), ergogenic (physical performance-enhancing), or nootropic (cognitive-enhancing) properties; it is also used recreationally or in social settings. Caffeine acts by blocking the binding of adenosine at a number of adenosine receptor types, inhibiting the centrally depressant effects of adenosine and enhancing the release of acetylcholine. Caffeine has a three-dimensional structure similar to that of adenosine, which allows it to bind and block its receptors. Caffeine also increases cyclic AMP levels through nonselective inhibition of phosphodiesterase, increases calcium release from intracellular stores, and antagonizes GABA receptors, although these mechanisms typically occur at concentrations beyond usual human consumption.

Caffeine is a bitter, white crystalline purine, a methylxanthine alkaloid, and is chemically related to the adenine and guanine bases of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). It is found in the seeds, fruits, nuts, or leaves of a number of plants native to Africa, East Asia, and South America and helps to protect them against herbivores and from competition by preventing the germination of nearby seeds, as well as encouraging consumption by select animals such as honey bees. The most common sources of caffeine for human consumption are the tea leaves of the Camellia sinensis plant and the coffee bean, the seed of the Coffea plant. Some people drink beverages containing caffeine to relieve or prevent drowsiness and to improve cognitive performance. To make these drinks, caffeine is extracted by steeping the plant product in water, a process called infusion. Caffeine-containing drinks, such as tea, coffee, and cola, are consumed globally in high volumes. In 2020, almost 10 million tonnes of coffee beans were consumed globally. Caffeine is the world's most widely consumed psychoactive drug. Unlike most other psychoactive substances, caffeine remains largely unregulated and legal in nearly all parts of the world. Caffeine is also an outlier as its use is seen as socially acceptable in most cultures and is encouraged in some.

Animal consciousness, or animal awareness, is the quality or state of self-awareness within an animal, or of being aware of an external object or of something within itself. In humans, consciousness has been defined as: sentience, awareness, subjectivity, qualia, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind. Despite the difficulty in definition, many philosophers believe there is a broadly shared underlying intuition about what consciousness is.

The topic of animal consciousness is beset with a number of difficulties. It poses the problem of other minds in an especially severe form because animals, lacking the ability to use human language, cannot communicate their experiences. It is also difficult to reason objectively about the question because a denial that an animal is conscious is often taken to imply that they do not feel, their life has no value, and that harming them is not morally wrong. For example, the 17th-century French philosopher René Descartes is sometimes criticised for enabling animal mistreatment through his animal machine view, which claimed that only humans are conscious.

Arousal is the physiological and psychological state of being awoken or of sense organs stimulated to a point of perception. It involves activation of the ascending reticular activating system (ARAS) in the brain, which mediates wakefulness, the autonomic nervous system, and the endocrine system, leading to increased heart rate and blood pressure and a condition of sensory alertness, desire, mobility, and reactivity.

Arousal is mediated by several neural systems. Wakefulness is regulated by the ARAS, which is composed of projections from five major neurotransmitter systems that originate in the brainstem and form connections extending throughout the cortex; activity within the ARAS is regulated by neurons that release the neurotransmitters norepinephrine, acetylcholine, dopamine, serotonin and histamine.

Iatromantis is a Greek word whose literal meaning is most simply rendered "physician-seer." The iatromantis, a form of Greek "shaman", is related to other semimythical figures such as Abaris, Aristeas, Epimenides, and Hermotimus.In the classical period, Aeschylus uses the word to refer to Apollo and to Asclepius, Apollo's son.

According to Peter Kingsley, iatromantis figures belonged to a wider Greek and Asian shamanic tradition with origins in Central Asia. A main ecstatic, meditative practice of these healer-prophets was incubation (ἐγκοίμησις, enkoimesis). More than just a medical technique, incubation reportedly allowed a human being to experience a fourth state of consciousness different from sleeping, dreaming, or ordinary waking: a state that Kingsley describes as “consciousness itself” and likens to the turiya or samādhi of the Indian yogic traditions. Kingsley identifies the Greek pre-Socratic philosopher Parmenides as an iatromantis. This identification has been described by Oxford academic Mitchell Miller as "fascinating" but also as "very difficult to assess as a truth claim".