A drug-related blackout is a phenomenon caused by the intake of any substance or medication in which short term and long term memory creation is impaired, therefore causing a complete inability to recall the past. Blackouts are most frequently associated with GABAergic drugs. Blackouts are frequently described as having effects similar to that of anterograde amnesia, in which the subject cannot recall any events after the event that caused amnesia. Research on alcohol blackouts was begun by E. M. Jellinek in the 1940s. Using data from a survey of Alcoholics Anonymous (AA) members, he came to believe that blackouts would be a good determinant of alcoholism. However, there are conflicting views whether this is true. The negative psychological effects of an alcohol-related blackout are often worsened by those who suffer from anxiety disorders. Impairment of the liver will also allow more alcohol to reach the brain and hasten the individual's blackout.

The term "blackout" can also refer to a complete loss of consciousness, or syncope.

Acute alcohol poisoning is a related medical term used to indicate a dangerously high concentration of alcohol in the blood, high enough to induce coma, respiratory depression, or even death. It is considered a medical emergency. The term is mostly used by healthcare providers. Toxicologists use the term "alcohol intoxication" to discriminate between alcohol and other toxins.

The signs and symptoms of acute alcohol poisoning include:

- severe confusion, unpredictable behavior and stupor

- sudden lapses into and out of unconsciousness or semi-consciousness (with later alcoholic amnesia)

- vomiting while unconscious or semi-conscious

- seizures

- respiratory depression (fewer than eight breaths a minute)

- pale, bluish, cold and clammy skin due to insufficient oxygen

Blackouts can generally be divided into 2 categories, "en bloc" blackouts and "fragmentary" blackouts. En bloc blackouts are classified by the inability to later recall any memories from the intoxication period, even when prompted. These blackouts are characterized also by the ability to easily recall things that have occurred within the last 2 minutes, yet being unable to recall anything prior to this period. As such, a person experiencing an en bloc blackout may not appear to be doing so, as they can carry on conversations or even manage to accomplish difficult feats. It is difficult to determine the end of this type of blackout as sleep typically occurs before they end, although it is possible for an en bloc blackout to end if the sufferer has stopped drinking in the meantime. Fragmentary blackouts are characterized by a person having the ability to recall certain events from an intoxicated period, and yet being unaware that other memories are missing until reminded of the existence of those 'gaps' in memory. Research indicates that such fragmentary blackouts, also known as brownouts, are far more common than en bloc blackouts. Memory impairment during acute intoxication involves dysfunction of episodic memory, a type of memory encoded with spatial and social context. Recent studies have shown that there are multiple memory systems supported by discrete brain regions, and the acute effects of alcohol and learning and memory may result from alteration of the hippocampus and related structures on a cellular level. A rapid increase in blood alcohol concentration (BAC) is most consistently associated with the likelihood of a blackout. However, not all subjects experience blackouts which implies that genetic factors play a role in determining central nervous system (CNS) vulnerability to the effects of alcohol. The former may predispose an individual to alcoholism, as altered memory function during intoxication may affect an individual’s alcohol expectancy, one may perceive positive aspects of intoxication while unintentionally ignoring the negative aspects.

Alcohol intoxication, also known as drunkenness among other names, is a physiological condition that may result in psychological alterations of consciousness. Drunkenness is induced by the ingestion or consumption of alcohol in a living body. Alcohol intoxication is the result of alcohol entering the bloodstream faster than it can be metabolized by the body. Metabolism results in breaking down the ethanol into non-intoxicating byproducts.

Some effects of alcohol intoxication, such as euphoria and lowered social inhibition, are central to alcohol's desirability as a beverage and its history as one of the world's most widespread recreational drugs. Despite this widespread use and alcohol's legality in most countries, many medical sources tend to describe any level of alcohol intoxication as a form of poisoning due to ethanol's damaging effects on the body in large doses. Some religions consider alcohol intoxication to be a sin.

Symptoms of alcohol intoxication include euphoria, flushed skin, and decreased social inhibition at lower doses, with larger doses producing progressively severe impairments of balance, and decision-making ability as well as nausea or vomiting from alcohol's disruptive effect on the semicircular canals of the inner ear and chemical irritation of the gastric mucosa.

Sufficiently extreme levels of blood-borne alcohol may result in coma or death.

Ethanol is the type of alcohol found in alcoholic beverages. It is a volatile, flammable, colorless liquid that acts as a central nervous system depressant. Ethanol can impair different types of memory.

Individuals with an alcohol use disorder will often complain of difficulty with interpersonal relationships, problems at work or school, and legal problems. Additionally, people may complain of irritability and insomnia. Alcohol abuse is also an important cause of chronic fatigue.

Signs of alcohol abuse are related to alcohol's effects on organ systems. However, while these findings are often present, they are not necessary to make a diagnosis of alcohol abuse. Signs of alcohol abuse show its drastic effects on the central nervous system, including inebriation and poor judgment; chronic anxiety, irritability, and insomnia. Alcohol's effects on the liver include elevated liver function tests (classically AST is at least twice as high as ALT). Prolonged use leads to cirrhosis and liver failure. With cirrhosis, patients develop an inability to process hormones and toxins. The skin of a patient with alcoholic cirrhosis can feature cherry angiomas, palmar erythema and — in acute liver failure — jaundice and ascites. The derangements of the endocrine system lead to the enlargement of the male breasts. The inability to process toxins leads to liver disease, such as hepatic encephalopathy.

Alcohol abuse can result in brain damage which causes impairments in executive functioning such as impairments to working memory, visuospatial skills, and can cause an abnormal personality as well as affective disorders to develop. Binge drinking is associated with individuals reporting fair to poor health compared to non-binge drinking individuals and which may progressively worsen over time. Alcohol also causes impairment in a person's critical thinking. A person's ability to reason in stressful situations is compromised, and they seem very inattentive to what is going on around them. Social skills are significantly impaired in people suffering from alcoholism due to the neurotoxic effects of alcohol on the brain, especially the prefrontal cortex area of the brain. The social skills that are impaired by alcohol abuse include impairments in perceiving facial emotions, difficulty with perceiving vocal emotions and theory of mind deficits; the ability to understand humour is also impaired in alcohol abusers. Adolescent binge drinkers are most sensitive to damaging neurocognitive functions especially executive functions and memory. People who abuse alcohol are less likely to survive critical illness with a higher risk for having sepsis and were more likely to die during hospitalization.

Alcohol abuse is a previous psychiatric diagnosis in which there is recurring harmful use of alcohol despite its negative consequences. In 2013 it was reclassified as alcohol use disorder (alcoholism) along with alcohol dependence. There are two types of alcohol abuse, those who have anti-social and pleasure-seeking tendencies, and those who are anxiety-ridden people who are able to go without drinking for long periods of time but are unable to control themselves once they start. Binge drinking is another form of alcohol abuse. According to surveys, the heaviest drinkers are the United Kingdom's adolescents. In 2013, 139,000 deaths globally were directly due to alcohol abuse and an additional 384,000 to cirrhosis from excess alcohol consumption.

Binge drinking, or heavy episodic drinking, is a modern epithet for drinking alcoholic beverages with an intention of becoming intoxicated by heavy consumption of alcohol over a short period of time.

Binge drinking is a style of drinking that is popular in several countries worldwide, and overlaps somewhat with social drinking since it is often done in groups. The degree of intoxication, however, varies between and within various cultures that engage in this practice. A binge on alcohol can occur over hours, last up to several days, or in the event of extended abuse, even weeks. Due to the long-term effects of alcohol misuse, binge drinking is considered to be a major public health issue.

Binge drinking is associated with a profound social harm, economic costs as well as increased disease burden. Binge drinking is more common in males, during adolescence and young adulthood. Heavy regular binge drinking is associated with adverse effects on neurologic, cardiac, gastrointestinal, hematologic, immune, musculoskeletal organ systems as well as increasing the risk of alcohol induced psychiatric disorders. A US-based review of the literature found that up to one-third of adolescents binge-drink, with six percent reaching the threshold of having an alcohol-related substance use disorder. Approximately one in 25 women binge-drinks during pregnancy, which can lead to fetal alcohol syndrome and fetal alcohol spectrum disorders. Binge drinking during adolescence is associated with traffic accidents and other types of accidents, violent behavior as well as suicide. The more often a child or adolescent binge drinks and the younger they are the more likely that they will develop an alcohol use disorder including alcoholism. A large number of adolescents who binge-drink also consume other psychotropic substances.

Chronic use of alcohol used to induce sleep can lead to insomnia: frequent moving between sleep stages occurs, with awakenings due to headaches and diaphoresis. Stopping chronic alcohol abuse can also lead to profound disturbances of sleep with vivid dreams. Chronic alcohol abuse is associated with NREM stage 3 and 4 sleep as well as suppression of REM sleep and REM sleep fragmentation. During withdrawal REM sleep is typically exaggerated as part of a rebound effect.

Essential tremors—or, in the case of essential tremors on a background of family history of essential tremors, familial tremors—can be temporarily relieved in up to two-thirds of patients by drinking small amounts of alcohol.

Ethanol is known to activate aminobutyric acid type A (GABAA) and inhibit N-methyl-D-aspartate (NMDA) glutamate receptors, which are both implicated in essential tremor pathology and could underlie the ameliorative effects. Additionally, the effects of ethanol have been studied in different animal essential tremor models. (For more details on this topic, see Essential tremor.)

Stolle, Sack and Thomasius define binge drinking as episodic excessive drinking. There is currently no worldwide consensus on how many drinks constitute a "binge", but in the United States, the term has been described in academic research to mean consuming five or more standard drinks (male), or four or more drinks (female), over a 2-hour period. In 2015, the US Centers for Disease Control and Prevention, citing the National Institute on Alcohol Abuse and Alcoholism, defines binge drinking as "a pattern of drinking that brings a person’s blood alcohol concentration (BAC) to 0.08 grams percent or above. This typically happens when men consume 5 or more drinks, and when women consume 4 or more drinks, in about 2 hours." and estimated that about 16% of American adults met these binge drinking criteria four times per month. One 2001 definition from the publication "Psychology of Addictive Behavior" states that 5 drinks for men and 4 drinks for women must be consumed on one occasion at least once in a two-week period for it to be classed as binge drinking. This is colloquially known as the "5/4 definition", and depending on the source, the timeframe can vary. In the United Kingdom, binge drinking is defined by one academic publication as drinking more than twice the daily limit, that is, drinking eight units or more for men or six units or more for women (roughly equivalent to five or four American standard drinks, respectively). In Australia, binge drinking is also known as risky single occasion drinking (RSOD) and can be classified by the drinking of seven or more standard drinks (by males) and 5 or more standard drinks (by females) within a single day. When BEACH (Bettering the Evaluation of care and health) conducted a study which gathered information of people over the age of 18, it defined binge drinkers as those who consumed six or more standard drinks on one occasion whether that be weekly or monthly.

The above definitions are limited in that they do not take into account the time period over which the drinking occurs or the body mass of the person drinking. A person could be defined as a binge drinker even if he or she never becomes intoxicated. The term, however, has succeeded in drawing public awareness to the problem of excess drinking..

Other, less common definitions rely on blood alcohol concentration (BAC). For example, the National Institute on Alcohol Abuse and Alcoholism (NIAAA) defines the term "binge drinking" as a pattern of drinking that brings a person’s blood alcohol concentration (BAC) to 0.08 grams percent or above. Whatever the numerical definition used, heavy drinking or rapid consumption over a short period of time with the intention of becoming intoxicated is often implied when the term is used colloquially, since four or five drinks consumed over the course of a whole day and as an accompaniment to meals will not have the same effects as the same amount consumed over a couple of hours on an empty stomach.

An alternative colloquial term for binge drinking, "going on a bender", formerly implied a drinking spree of several days.

Sleepwalking, also known as somnambulism or noctambulism, is a phenomenon of combined sleep and wakefulness. It is classified as a sleep disorder belonging to the parasomnia family. It occurs during slow wave sleep stage, in a state of low consciousness, with performance of activities that are usually performed during a state of full consciousness. These activities can be as benign as sitting up in bed, walking to a bathroom, and cleaning, or as hazardous as cooking, driving, violent gestures, grabbing at hallucinated objects, or even homicide.

Although sleepwalking cases generally consist of simple, repeated behaviours, there are occasionally reports of people performing complex behaviours while asleep, although their legitimacy is often disputed. Sleepwalkers often have little or no memory of the incident, as their consciousness has altered into a state in which it is harder to recall memories. Although their eyes are open, their expression is dim and glazed over. This may last from 30 seconds to 30 minutes.

Sleepwalking occurs during slow-wave sleep (N3) of non-rapid eye movement sleep (NREM sleep) cycles. It typically occurs within the first third of the night when slow-wave sleep is most prominent. Usually, it will occur once in a night, if at all.

Anterograde amnesia is a loss of the ability to create new memories after the event that caused the amnesia, leading to a partial or complete inability to recall the recent past, while long-term memories from before the event remain intact. This is in contrast to retrograde amnesia, where memories created prior to the event are lost while new memories can still be created. Both can occur together in the same patient. To a large degree, anterograde amnesia remains a mysterious ailment because the precise mechanism of storing memories is not yet well understood, although it is known that the regions involved are certain sites in the temporal cortex, especially in the hippocampus and nearby subcortical regions.

People with anterograde amnesic syndromes may present with widely varying degrees of forgetfulness. Some with severe cases have a combined form of anterograde and retrograde amnesia, sometimes called global amnesia.

In the case of drug-induced amnesia, it may be short-lived and patients can recover from it. In the other case, which has been studied extensively since the early 1970s, patients often have permanent damage, although some recovery is possible, depending on the nature of the pathophysiology. Usually, some capacity for learning remains, although it may be very elementary. In cases of pure anterograde amnesia, patients have recollections of events prior to the injury, but cannot recall day-to-day information or new facts presented to them after the injury occurred.

In most cases of anterograde amnesia, patients lose declarative memory, or the recollection of facts, but they retain nondeclarative memory, often called procedural memory. For instance, they are able to remember and in some cases learn how to do things such as talking on the phone or riding a bicycle, but they may not remember what they had eaten earlier that day for lunch. One extensively studied anterograde amnesiac patient, codenamed H.M., demonstrated that despite his amnesia preventing him from learning new declarative information, procedural memory consolidation was still possible, albeit severely reduced in power. He, along with other patients with anterograde amnesia, were given the same maze to complete day after day. Despite having no memory of having completed the maze the day before, unconscious practice of completing the same maze over and over reduced the amount of time needed to complete it in subsequent trials. From these results, Corkin et al. concluded despite having no declarative memory (i.e. no conscious memory of completing the maze exists), the patients still had a working procedural memory (learning done unconsciously through practice). This supports the notion that declarative and procedural memory are consolidated in different areas of the brain. In addition, patients have a diminished ability to remember the temporal context in which objects were presented. Certain authors claim the deficit in temporal context memory is more significant than the deficit in semantic learning ability (described below).

In the study "sleepwalking and sleep terrors in prepubera children", it was found that, if a child had another sleep disorder such as restless leg syndrome (RLS) or sleep-disorder breathing (SDB), there was a greater chance of sleepwalking. The study found that children with chronic parasomnias may often also present SDB or, to a lesser extent, RLS. Furthermore, the disappearance of the parasomnias after the treatment of the SDB or RLS periodic limb movement syndrome suggests that the latter may trigger the former. The high frequency of SDB in family members of children with parasomnia provided additional evidence that SDB may manifest as parasomnias in children. Children with parasomnias are not systematically monitored during sleep, although past studies have suggested that patients with sleep terrors or sleepwalking have an elevated level of brief EEG arousals. When children receive polysomnographies, discrete patterns (e.g., nasal flow limitation, abnormal respiratory effort, bursts of high or slow EEG frequencies) should be sought; apneas are rarely found in children. Children's respiration during sleep should be monitored with nasal cannula/pressure transducer system and/or esophageal manometry, which are more sensitive than the thermistors or thermocouples currently used in many laboratories. The clear, prompt improvement of severe parasomnia in children who are treated for SDB, as defined here, provides important evidence that subtle SDB can have substantial health-related significance. Also noteworthy is the report of familial presence of parasomnia. Studies of twin cohorts and families with sleep terror and sleepwalking suggest genetic involvement of parasomnias. RLS and SDB have been shown to have familial recurrence. RLS has been shown to have genetic involvement.

In some cases, sleepwalking in adults may be a symptom of a psychological disorder. One study suggests higher levels of dissociation in adult sleepwalkers, since test subjects scored unusually high on the hysteria portion of the "Crown-Crisp Experiential Index". Another suggested that "A higher incidence [of sleepwalking events] has been reported in patients with schizophrenia, hysteria and anxiety neuroses". Also, patients with migraine headaches or Tourette Syndrome are 4–6 times more likely to sleepwalk.

Alcohol has shown to have "some" long-term effect on working memory. Findings have shown that for working memory to be substantially affected, long-term, heavy drinking must be sustained over a long period of time as up to one drink per day does not impair cognitive function and may actually decrease the risk of cognitive decline. Furthermore, chronic alcoholism is associated with impairment in sustained attention and visual working memory. Thus, alcoholics have reduced ability, but not necessarily "inability", to perform these executive tasks, assumed to be subserved by regions of prefrontal cortex. While it may not serve as a surprise that chronic alcoholism has been linked to decreased cognitive function including working memory, one surprising finding is not only that even moderate levels of alcohol consumption during pregnancy were shown to have an adverse effect on the child's working memory when tested at 7.5 years of age, but that working memory may be the most important aspect of attention that is adversely affected by prenatal alcohol exposure.

There are several terms which were in general use, but are no longer recommended.

Drowning is most often quick and unspectacular. Its media depictions as a loud, violent struggle have much more in common with distressed non-swimmers, who may well drown but have not yet begun to do so. In particular, an asphyxiating person is seldom able to call for help. The instinctive drowning response covers many signs or behaviors associated with drowning or near-drowning:

- Head low in the water, mouth at water level

- Head tilted back with mouth open

- Eyes glassy and empty, unable to focus

- Eyes open, with fear evident on the face

- Hyperventilating or gasping

- Trying to swim in a particular direction but not making headway

- Trying to roll over on the back to float

- Uncontrollable movement of arms and legs, rarely out of the water.

Frank Pia, a lifeguard and researcher of rescue techniques and drowning, notes that drowning begins at the point a person is unable to keep their mouth above water; inhalation of water takes place at a later stage. Most people demonstrating the instinctive drowning response do not show obvious prior evidence of distress.

The 1971 Iraq poison grain disaster was a mass methylmercury poisoning incident that began in late 1971. Grain treated with a methylmercury fungicide and never intended for human consumption was imported into Iraq as seed grain from Mexico and the United States. Due to a number of factors, including foreign-language labelling and late distribution within the growing cycle, this toxic grain was consumed as food by Iraqi residents in rural areas. People suffered from paresthesia (numbness of skin), ataxia (lack of coordination of muscle movements) and vision loss, symptoms similar to those seen when Minamata disease affected Japan. The recorded death toll was 459 people, but figures at least ten times greater have been suggested. The 1971 poisoning was the largest mercury poisoning disaster when it occurred, with cases peaking in January and February 1972 and stopping by the end of March.

Reports after the disaster recommended tighter regulation, better labelling and handling of mercury-treated grain, and wider involvement of the World Health Organization in monitoring and preventing poisoning incidents. Investigation confirmed the particular danger posed to fetuses and young children.

Asphyxia or asphyxiation is a condition of severely deficient supply of oxygen to the body that arises from abnormal breathing. An example of asphyxia is choking. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that can induce asphyxia, all of which are characterized by an inability of an individual to acquire sufficient oxygen through breathing for an extended period of time. Asphyxia can cause coma or death.

In 2015 about 9.8 million cases of unintentional suffocation occurred which resulted in 35,600 deaths. The word asphyxia is from Ancient Greek "without" and , "squeeze" (throb of heart).

Situations that can cause asphyxia include but are not limited to: the constriction or obstruction of airways, such as from asthma, laryngospasm, or simple blockage from the presence of foreign materials; from being in environments where oxygen is not readily accessible: such as underwater, in a low oxygen atmosphere, or in a vacuum; environments where sufficiently oxygenated air is present, but cannot be adequately breathed because of air contamination such as excessive smoke.

Other causes of oxygen deficiency include

but are not limited to:

- Acute respiratory distress syndrome

- Carbon monoxide inhalation, such as that from a car exhaust and the smoke's emission from a lighted cigarette: carbon monoxide has a higher affinity than oxygen to the hemoglobin in the blood's red blood corpuscles, bonding with it tenaciously, and, in the process, displacing oxygen and preventing the blood from transporting oxygen around the body

- Contact with certain chemicals, including pulmonary agents (such as phosgene) and blood agents (such as hydrogen cyanide)

- Drowning

- Drug overdose

- Exposure to extreme low pressure or vacuum to the pattern (see space exposure)

- Hanging, specifically suspension or short drop hanging

- Self-induced hypocapnia by hyperventilation, as in shallow water or deep water blackout and the choking game

- Inert gas asphyxiation

- Congenital central hypoventilation syndrome, or primary alveolar hypoventilation, a disorder of the autonomic nervous system in which a patient must consciously breathe; although it is often said that persons with this disease will die if they fall asleep, this is not usually the case

- Respiratory diseases

- Sleep apnea

- A seizure which stops breathing activity

- Strangling

- Breaking the wind pipe.

- Prolonged exposure to chlorine gas