The internalizing disorders, with high levels of negative affectivity, include depressive disorders, anxiety disorders, obsessive-compulsive and related disorders, trauma and stressor-related disorders, and dissociative disorders. Others like bulimia, and anorexia also come under this category.

Physical symptoms include:

- palpitations

- anorexia

- dry mouth

- insomnia

- thoracic/chest pressure

- respiratory difficulties

- epigastric mass

- headache

- a whole-body sensation of heat (distinct from heat intolerance, a symptom of hyperthyroidism)

Psychological symptoms include:

- being easily startled

- externalization of anger, also known in Korean as "bun" (분, 憤, "eruption of anger"), a Korean culture-related sentiment related to social unfairness

- generally sad mood

- frequent sighing

- a feeling of "eok-ul" (억울, 抑鬱, [feeling of] unfairness)

- being easily agitated

- feelings of guilt

- feelings of impending doom

Diagnosed patients may also have a medical history of prior major depressive disorder, dysthymic disorder, anxiety disorders, somatoform disorders, or adjustment disorder according to the "Diagnostic and Statistical Manual of Mental Disorders", fourth edition (DSM-IV) criteria.

Diagnosed patients are most likely to be middle-aged, post-menopausal women with low socio-economic status.

Behaviors that are apparent in those with internalizing disorders include depression, withdrawal, anxiety, and loneliness. There are also behavioral characteristics involved with internalizing disorders. Some behavioral abnormalities include poor self-esteem, suicidal behaviors, decreased academic progress, and social withdrawal. Internalizing one's problems, like sadness, can cause the problems to grow into larger burdens such as social withdrawal, suicidal behaviors or thoughts, and other unexplained physical symptoms.

Hwabyeong or Hwabyung is a Korean somatization disorder, a mental illness which arises when people are unable to confront their anger as a result of conditions which they perceive to be unfair.

Hwabyung is a colloquial and somewhat inaccurate name, as it refers to the etiology of the disorder rather than its symptoms or apparent characteristics. Hwabyung is known as a culture-bound syndrome. The word hwabyung is composed of "hwa" (the Sino-Korean word for "fire" which can also contextually mean "anger") and "byung" (the Sino-Korean word for "syndrome" or "illness"). In South Korea, it may also be called "ulhwabyeong" (), literally "depression anger illness". In one survey, 4.1% of the general population in a rural area in Korea were reported as having hwabyung. Another survey shows that about 35% of Korean workers are affected by this condition at some time.

Nocturnal sleep-related eating disorder (NSRED), also known as sleep-related eating disorder (SRED), sleep eating, or somnambulistic eating, is a combination of a parasomnia and an eating disorder. It is described as being in a specific category within somnambulism or a state of sleepwalking that includes behaviors connected to a person's conscious wishes or wants. Thus many times NSRED is a person's fulfilling of their conscious wants that they suppress; however, this disorder is difficult to distinguish from other similar types of disorders.

NSRED is closely related to night eating syndrome (NES) except for the fact that those suffering from NES are completely awake and aware of their eating and bingeing at night while those suffering from NSRED are sleeping and unaware of what they are doing. NES is primarily considered an eating disorder while NSRED is primarily considered a parasomnia; however, both are a combination of parasomnia and eating disorders since those suffering from NES usually have insomnia or difficulty sleeping and those suffering from NSRED experience symptoms similar to binge eating. Some even argue over whether NES and NSRED are the same or distinct disorders. Even though there have been debates over these two disorders, specialists have examined them to try to determine the differences. Dr. J. Winkelman noted several features of the two disorders that were similar, but he gave one important factor that make these disorders different. In his article "Sleep-Related Eating Disorder and Night Eating Syndrome: Sleep Disorders, Eating Disorders, Or both", Winkelman said, "Both [disorders] involve nearly nightly binging at multiple nocturnal awakenings, defined as excess calorie intake or loss of control over consumption." He also reported that both disorders have a common occurrence of approximately one to five percent of adults, have been predominantly found in women, with a young adult onset, have a chronic course, have a primary morbidity of weight gain, sleep disruption, and shame over loss of control over food intake, have familial bases, and have been observed to have comorbid depression and daytime eating disorders. However, Winkelman said, "The most prominent cited distinction between NES and SRED is the level of consciousness during nighttime eating episodes." Therefore, these two disorders are extremely similar with only one distinction between them. Doctors and psychologists have difficulty differentiating between NES and NSRED, but the distinction of a person's level of consciousness is what doctors chiefly rely on to make a diagnosis. One mistake that is often made is the misdiagnosis of NSRED for NES. However, even though NSRED is not a commonly known and diagnosed disease, many people suffer from it in differing ways while doctors work to find a treatment that works for everyone; several studies have been done on NSRED, such as the one conducted by Schenck and Mahowald. These studies, in turn, provide the basic information on this disorder including the symptoms, behaviors, and possible treatments that doctors are using today.

Somatic symptom disorders are a group of disorders, all of which fit the definition of physical symptoms similar to those observed in physical disease or injury for which there is no identifiable physical cause. As such, they are a diagnosis of exclusion. Somatic symptoms may be generalized in four major medical categories: neurological, cardiac, pain, and gastrointestinal somatic symptoms.

The symptoms of CANDLE syndrome can manifest themselves in a variety of different ways and combinations related to skin disorders, internal inflammatory responses, and fever-based conditions. The types of outwardly visible conditions involve facies not matching other known disorders, contracture of the joints, and skin lesions appearing across any part of the body. The multiple inflammatory developments include nonspecific lymphadenopathy, hepatosplenomegaly, and autoimmune hemolytic anemia. Other possible conditions are hypertriglyceridemia and lipodystrophy.

Other novel mutations resulting in the syndrome have also involved the manifestation of other conditions, such as Sweet's syndrome and pericarditis. Another case in 2015 showcased previously undescribed dental symptoms, such as microdontia and osteopenia of the jaw, along with a general case of diabetes mellitus.

The affective spectrum is a spectrum of affective disorders (mood disorders). It is a grouping of related psychiatric and medical disorders which may accompany bipolar, unipolar, and schizoaffective disorders at statistically higher rates than would normally be expected. These disorders are identified by a common positive response to the same types of pharmacologic treatments. They also aggregate strongly in families and may therefore share common heritable underlying physiologic anomalies.

Affective spectrum disorders include:

- Attention deficit hyperactivity disorder

- Bipolar disorder

- Body dysmorphic disorder

- Bulimia nervosa and other eating disorders

- Cataplexy

- Dysthymia

- Generalized anxiety disorder

- Hypersexuality

- Irritable bowel syndrome

- Impulse-control disorders

- Kleptomania

- Migraine

- Major depressive disorder

- Obsessive-compulsive disorder

- Oppositional defiant disorder

- Panic disorder

- Posttraumatic stress disorder

- Premenstrual dysphoric disorder

- Social anxiety disorder

- Fibromyalgia

The following may also be part of the spectrum accompanying affective disorders.

- Chronic pain

- Intermittent explosive disorder

- Pathological gambling

- Personality disorder

- Pyromania

- Substance abuse and addiction (includes alcoholism)

- Trichotillomania

Also, there are now studies linking heart disease.

Many of the terms above overlap. The American Psychiatric Association's definitions of these terms can be found in the "Diagnostic and Statistical Manual of Mental Disorders" (DSM).

Over the past thirty years, several studies have found that those afflicted with NSRED all have different symptoms and behaviors specific to them, yet they also all have similar characteristics that doctors and psychologists have identified to distinguish NSRED from other combinations of sleep and eating disorders such as night eating syndrome. Winkelman says that typical behaviors for patients with NSRED include: "Partial arousals from sleep, usually within 2 to 3 hours of sleep onset, and subsequent ingestion of food in a rapid or 'out of control' manner." They also will attempt to eat bizarre amalgamations of foods and even potentially harmful substances such as glue, wood, or other toxic materials. In addition, Schenck and Mahowald noted that their patients mainly ate sweets, pastas, both hot and cold meals, improper substances such as "raw, frozen, or spoiled foods; salt or sugar sandwiches; buttered cigarettes; and odd mixtures prepared in a blender."

During the handling of this food, patients with NSRED distinguish themselves, as they are usually messy or harmful to themselves. Some eat their food with their bare hands while others attempt to eat it with utensils. This occasionally results in injuries to the person as well as other injuries. After completing their studies, Schenck and Mahowald said, "Injuries resulted from the careless cutting of food or opening of cans; consumption of scalding fluids (coffee) or solids (hot oatmeal); and frenzied running into walls, kitchen counters, and furniture." A few of the more notable symptoms of this disorder include large amounts of weight gain over short periods of time, particularly in women; irritability during the day, due to lack of restful sleep; and vivid dreams at night. It is easily distinguished from regular sleepwalking by the typical behavioral sequence consisting of "rapid, 'automatic' arising from bed, and immediate entry into the kitchen." In addition, throughout all of the studies done, doctors and psychiatrists discovered that these symptoms are invariant across weekdays, weekends, and vacations as well as the eating excursions being erratically spread throughout a sleep cycle. Most people that suffer from this disease retain no control over when they arise and consume food in their sleep. Although some have been able to restrain themselves from indulging in their unconscious appetites, some have not and must turn to alternative methods of stopping this disorder. It is important for trained physicians to recognize these symptoms in their patients as quickly as possible, so those with NSRED may be treated before they injure themselves.

International Statistical Classification of Diseases and Related Health Problems, mostly known as "ICD", assigns codes to classify diseases, symptoms, complaints, social behaviors, injuries, and such medical-related findings.

ICD 10 classifies adjustment disorders under F40-F48 and under neurotic, stress-related and somatoform disorders.

Additional proposed somatic symptom disorders are:

- Abridged somatization disorder – at least 4 unexplained somatic complaints in men and 6 in women

- Multisomatoform disorder – at least 3 unexplained somatic complaints from the PRIME-MD scale for at least 2 years of active symptoms

These disorders have been proposed because the recognized somatic symptom disorders are either too restrictive or too broad. In a study of 119 primary care patients, the following prevalences were found:

- Somatization disorder – 1%

- Abridged somatization disorder – 6%

- Multisomatoform disorder – 24%

- Undifferentiated somatoform disorder – 69%

The basis of the diagnosis is the presence of a precipitating stressor and a clinical evaluation of the possibility of symptom resolution on removal of the stressor due to the limitations in the criteria for diagnosing AD. In addition, the diagnosis of AD is less clear when patients are exposed to stressors long-term, because this type of exposure is associated with AD and major depressive disorder (MDD) and generalized anxiety disorder (GAD).

Some signs and criteria used to establish a diagnosis are important. First, the symptoms must clearly follow a stressor. The symptoms should be more severe than would be expected. There should not appear to be other underlying disorders. The symptoms that are present are not part of a normal grieving for the death of family member or other loved one.

Adjustment disorders have the ability to be self-limiting. Within five years of when they are originally diagnosed, approximately 20%–50% of the sufferers go on to be diagnosed with psychiatric disorders that are more serious.

Disorders considered in origin include:

1. Intellectual disability (ID) or intellectual and developmental disability (IDD), previously called mental retardation

2. Autism spectrum disorders, such as Asperger's syndrome or Kanner syndrome

3. Motor disorders including developmental coordination disorder and stereotypic movement disorder Tic disorders including Tourette's syndrome

4. Traumatic brain injury (including congenital injuries such as those that cause cerebral palsy)

5. Communication, speech and language disorders

6. genetic disorders, such as fragile-X syndrome, Down syndrome, attention deficit hyperactivity disorder, schizophrenia, schizotypal disorder, hypogonadotropic hypogonadal syndromes

7. disorders due to neurotoxicants like fetal alcohol spectrum disorder, Minamata disease caused by mercury, behavioral disorders including conduct disorder etc caused by other heavy metals, such as lead, chromium, platinum etc, hydrocarbons like dioxin, PBDEs and PCBs, medications and illegal drugs, like cocaine and others.

Neurodevelopmental disorders are impairments of the growth and development of the brain or central nervous system. A narrower use of the term refers to a disorder of brain function that affects emotion, learning ability, self-control and memory and that unfolds as an individual develops and grows.

The term is sometimes erroneously used as an exclusive synonym for autism spectrum disorders.

Externalizing disorders often involve emotion dysregulation problems and impulsivity that are manifested as antisocial behavior and aggression in opposition to authority, societal norms, and often violate the rights of others. Some examples of externalizing disorder symptoms include, often losing one's temper, excessive verbal aggression, physical aggression to people and animals, destruction of property, theft, and deliberate fire setting. As with all DSM-5 mental disorders, an individual must have functional impairment in at least one domain (e.g., academic, occupational, social relationships, or family functioning) in order to meet diagnostic criteria for an externalizing disorder. Moreover, an individual's symptoms should be atypical for their cultural and environmental context and physical medical conditions should be ruled out before an externalizing disorder diagnosis is considered. Diagnoses must be made by qualified mental health professionals. DSM-5 classifications of externalizing disorders are listed herein, however, can also be used to classify externalizing disorders. More specific criteria and examples of symptoms for various externalizing disorders can be found in the DSM-5.

There are no specific criteria for "externalizing behavior" or "externalizing disorders." Thus, there is no clear classification of what constitutes an externalizing disorder in the DSM-5. Attention-deficit/hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), conduct disorder (CD), antisocial personality disorder(ASPD), pyromania, kleptomania, intermittent explosive disorder (IED), and substance-related disorders are frequently referred to as externalizing disorders. Disruptive mood dysregulation disorder has also been posited as an externalizing disorder, but little research has examined and validated it to date given its recent addition to the DSM-5, and thus, it is not included further herein.

Examples of symptoms of childbirth-related posttraumatic stress disorder include: intrusive symptoms such as flashbacks and nightmares, as well as symptoms of avoidance (including amnesia for the whole or parts of the event), problems in developing a mother-child attachment, not having sexual intercourse in order to prevent another pregnancy, and avoidance of birth and pregnancy related issues. Symptoms of increasing stress can be sweating, trembling, being irritated, and sleep disturbances.

Chronic Atypical Neutrophilic Dermatosis with Lipodystrophy and Elevated Temperature (CANDLE) syndrome is an autosomal recessive disorder that presents itself via various autoinflammatory responses throughout the body, multiple types of skin lesions, and recurrent long-term fever symptoms. The current known cause for the disorder is a mutation in the PSMB8 gene or mutations in other closely related genes. The syndrome was first named and classified in March 2010 after four patients were reviewed with similar symptoms. There have been approximately 30 cases ever reported in the scientific literature, as of 2015.

Typical deficiencies may include problems identifying, processing, describing, and working with one's own feelings, often marked by a lack of understanding of the feelings of others; difficulty distinguishing between feelings and the bodily sensations of emotional arousal; confusion of physical sensations often associated with emotions; few dreams or fantasies due to restricted imagination; and concrete, realistic, logical thinking, often to the exclusion of emotional responses to problems. Those who have alexithymia also report very logical and realistic dreams, such as going to the store or eating a meal. Clinical experience suggests it is the structural features of dreams more than the ability to recall them that best characterizes alexithymia.

Some alexithymic individuals may appear to contradict the above-mentioned characteristics because they can experience chronic dysphoria or manifest outbursts of crying or rage. However, questioning usually reveals that they are quite incapable of describing their feelings or appear confused by questions inquiring about specifics of feelings.

According to Henry Krystal, individuals suffering from alexithymia think in an operative way and may appear to be superadjusted to reality. In psychotherapy, however, a cognitive disturbance becomes apparent as patients tend to recount trivial, chronologically ordered actions, reactions, and events of daily life with monotonous detail. In general, these individuals lack imagination, intuition, empathy, and drive-fulfillment fantasy, especially in relation to objects. Instead, they seem oriented toward things and even treat themselves as robots. These problems seriously limit their responsiveness to psychoanalytic psychotherapy; psychosomatic illness or substance abuse is frequently exacerbated should these individuals enter psychotherapy.

A common misconception about alexithymia is that affected individuals are totally unable to express emotions verbally and that they may even fail to acknowledge that they experience emotions. Even before coining the term, Sifneos (1967) noted patients often mentioned things like anxiety or depression. The distinguishing factor was their inability to elaborate beyond a few limited adjectives such as "happy" or "unhappy" when describing these feelings. The core issue is that people with alexithymia have poorly differentiated emotions limiting their ability to distinguish and describe them to others. This contributes to the sense of emotional detachment from themselves and difficulty connecting with others, making alexithymia negatively associated with life satisfaction even when depression and other confounding factors are controlled for.

X-linked thrombocytopenia is typically diagnosed in infancy. The disease presents as a bleeding disorder with easy bruising, mucosal bleeding, such as nosebleeds, and mild to severe anemia. Anemia is a condition in which there is an insufficient number of red blood cells to carry adequate levels of oxygen to the body’s tissues. X-linked thrombocytopenia is considered to be the milder phenotype of the "WAS"-related disorders. As age increases, the severity of symptoms tends to decrease. However, individuals with X-linked thrombocytopenia have an increased risk for life-threatening brain hemorrhages and spontaneous bleeding.

Genetic changes are related to the following types of collagenopathy, types II and XI.

The system for classifying collagenopathies is changing as researchers learn more about the genetic causes of these disorders.The clinical features of the type II and XI collagenopathies vary among the disorders, but there is considerable overlap. Common signs and symptoms include problems with bone development that can result in short stature, enlarged joints, spinal curvature, and arthritis at a young age. For some people, bone changes can be seen only on X-ray images. Problems with vision and hearing, as well as a cleft palate with a small lower jaw, are common. Some individuals with these disorders have distinctive facial features such as protruding eyes and a flat nasal bridge.

A spectrum disorder is a mental disorder that includes a range of linked conditions, sometimes also extending to include singular symptoms and traits. The different elements of a spectrum either have a similar appearance or are thought to be caused by the same underlying mechanism. In either case, a spectrum approach is taken because there appears to be "not a unitary disorder but rather a syndrome composed of subgroups". The spectrum may represent a range of severity, comprising relatively "severe" mental disorders through to relatively "mild and nonclinical deficits".

In some cases, a spectrum approach joins together conditions that were previously considered separately. A notable example of this trend is the autism spectrum, where conditions on this spectrum may now all be referred to as autism spectrum disorders. In other cases, what was treated as a single disorder comes to be seen (or seen once again) as comprising a range of types, a notable example being the bipolar spectrum. A spectrum approach may also expand the type or the severity of issues which are included, which may lessen the gap with other diagnoses or with what is considered "normal". Proponents of this approach argue that it is in line with evidence of gradations in the type or severity of symptoms in the general population, and helps reduce the stigma associated with a diagnosis. Critics, however, argue that it can take attention and resources away from the most serious conditions associated with the most disability, or on the other hand could unduly medicalize problems which are simply challenges people face in life.

Childbirth-related PTSD is not a recognized diagnosis in the "Diagnostic and Statistical Manual of Mental Disorders". Many women presenting with symptoms of PTSD after childbirth are misdiagnosed with postpartum depression or adjustment disorders. These diagnoses can lead to inadequate treatment.

Symptoms of OBS vary with the disease that is responsible. However, the more common symptoms of OBS are confusion; impairment of memory, judgment, and intellectual function; and agitation. Often these symptoms are attributed to psychiatric illness, which causes a difficulty in diagnosis.

Some of the possible symptoms that can occur with metabolic disorders are: lethargy, weight loss, jaundice, seizures, to name a few. The symptoms expressed would vary with the type of metabolic disorder. There are four categories of symptoms: acute symptoms, late-onset acute symptoms, progressive general symptoms and permanent symptoms.