Psychiatric Disorder-It is a clinically significant psychological or behavioral syndrome that causes significant distress (subjective symptomatology), disability (objective symptomatology), or loss of freedom and which is not merely a socially deviant behavior or an expected response to a stressful life event (e.g. loss of a loved one)

Some Psychiatric Disorders are-
 
1 Substance Use Disorder-Drug (substance) is defined as any substance that when taken into the living organism may modify one or more of its functions.
The major dependence producing drugs are alcohol, opioids, cannabis, cocaine, LSD, amphetamine, nicotine, caffeine
Substance use disorders are
- Alcohol use disorder    
- Opioid use disorder     
- Cannabis use disorder
- Cocaine use disorder  
- LSD use disorder
- Amphetamine use disorder  

One of these disorders is as follows
Alcohol use disorder- Alcohol dependence was earlier called as alcoholism. Alcohol dependence is more common in males & has an onset in late second or early third decade The course is insidious There is often an associated abuse or dependence of other drugs It the onset occurs late in life especially after 40 years of age, underlying mood disorders or brain diseases should be looked for.
Cocaine use disorder-Cocaine is an alkaloid derived from the coca bush. Cocaine can be administered orally, intranasally, by smoking or parenterally, depending on the preparation available. Cocaine use produces a very mild physical, but a very strong psychic, dependence.
                                                                              

2. Sexual addiction- is not a recognized diagnosis the DSM-IV. However, is has been developed by researchers to come to mean a person who compulsively seeks out sexual experiences and who’s behavior becomes impaired if they are unable to gratify their sexual impulses.
                                                                              

3. Sleep disorders-The types of sleep disorder are legion.
The sleep disorders are divided in 2 subtypes
    A) Dyssomnias    B) Parasomnias

DYSSOMNIAS-are those sleep disorders which are characterized by disturbances in the amount, quality or timing of sleep. These are the commonest disorders. One of those is as follows
Insomnia- It is as DIMS (Disorder of Initiation &/or Maintenance of Sleep) It means difficulty in initiating sleep. This includes frequent awakenings during the night & early morning awakenings.
Common causes of Insomnia are heart diseases, respiratory diseases, old age, and drug or alcohol withdrawal syndrome.

Mood Disorders-The emotions can be described as two main types
a) Affect- which is a short-lived emotional response to an idea or an event
b) Mood- which is a sustained & pervasive emotional response which colors
    the whole psychic life. So according to these definitions, depression & mania are
   ‘Mood disorders’
Mood disorders are classified as:
1) Bipolar mood (affective) disorder     2) Manic episode
3) Recurrent depressive disorder        4) Depressive episode 

Bipolar mood disorder-This disorder earlier known as manic depressive psychosis (MDP) is characterized by recurrent episodes of mania episodes & depression in the same patient at different times. Bipolar mood disorder is further classified in to-
Bipolar I-  characterized by episodes of severe mania & severe depression
Bipolar II- characterized by hypomania(not requiring hospitalization) & severe depression.

Depressive episode-The most important feature is the sadness of mood or loss of interest in almost all activities. The life time risk of depression in males is 8-12% & in females is 20-26%; though the life time risk of major depression or depressive episode is about 8%        
                                                                           
Anxiety Disorder-Anxiety is the commonest psychiatric symptom in clinical practice & anxiety disorders are one of the commonest psychiatric disorders. Anxiety is a normal phenomenon which is characterized by a state of apprehension or unease arising out of anticipation of danger
Symptoms of Anxiety-
Physical symptoms
-Motoric symptoms-Tremors, restlessness, muscle twitches, fearful facial expression
-Autonomic & visceral symptoms-Palpitations, trachycardia, sweating, flushes, dry  
 mouth, dizziness, diarrhea

Psychic symptoms-
1) cognitive symptoms-Poor concentration, distractibility, hyperarousal, 
    vigilance or scanning
2) Perceptual symptoms-Derealization, depersonalization 

Anxiety disorders are-
Generalized Anxiety Disorder-This is characterized by an insidious onset in the third decade & a stable, usually chronic course which may or may not be punctuated by repeated panic attacks (episodes of acute anxiety)
The symptoms if anxiety should last for at least a period of 6 months for a diagnosis of generalized anxiety disorder to be made. It is commonest psychiatric disorder in the general population

Panic disorder-This is characterized by discrete episodes of acute anxiety The onset is usually in early third decade with often a chronic course The panic attacks occurs recurrently every few days.

Obsessive-Compulsive disorder-
An obsessive is defined as an idea, impulse, or image which intrudes into conscious awareness repeatedly. Differentiation has to be made from delusion & thought insertion.
A delusion is recognized as one’s own idea but is not recognized as ego-alien. Thought insertion is not thought of as one’s own idea but somebody else’s thought being forcibly inserted into one’s mind.
An obsession is usually associated with a compulsion. Compulsion is defined as a form of behavior which usually follows obsessions
psychiatry.