A psychiatrist is a medical doctor who trained in diagnosis, prevention, and treatment of mental, behavioral, and emotional disorders including schizophrenia, bipolar disorder, depression, eating disorders, and substance use disorders. Psychiatrists provide a wide range of treatments including psychological treatment also called psychotherapy or talking therapy, medication, and brain stimulation therapies such as electroconvulsive therapy. Psychiatrists assess all of the mental and physical symptoms by examining mental or physical status, brain imaging such as a computerized tomography (CT), or positron emission tomography (PET) scan, magnetic resonance imaging (MRI), and blood testing.

A psychologist is a medical doctor who trained in diagnosis, and treatment of a mental illness including schizophrenia, behavioral problems, learning difficulties, depression, and anxiety. Psychologists provide a wide range of treatments including psychological treatment also called psychotherapy or talking therapy, medication, behavioral, cognitive, cognitive-behavioral, interpersonal, humanistic, and psychodynamic therapy. A psychologist may also use the Diagnostic and Statistical Manual (DSM) criteria to diagnose the mental disease.

A sleep specialist is a professional medical doctor who has completed further training and education in the area of sleep medicine. Sleep medicine focuses on sleep, sleep-related conditions, sleep disorders including excessive snoring, sleep apnea, insomnia, narcolepsy (chronic, uncontrollable daytime sleepiness). They have a subspecialty within several medical specialties, including pulmonology, neurology, psychiatry, and internal medicine. They also diagnose and treat parasomnias (abnormal events occuring during sleep) such as bedwetting, nightmares, periodic limb movement disorder, sleep paralysis, sleepwalking, teeth grinding.

Somnology is the field which involves scientific study of sleep. It includes diagnoses, treatment, and study of sleep irregularities and disorders. Somnologists are the doctors trained or educated in diagnosing and treating sleep disorders. They diagnose patients by asking the patients to record a two-week sleep diary that involves the details of how much time they sleep and how their sleep was interrupted. Along with this, the doctor also performs the physical examination of the lung, throat, and heart. To solve the issues regarding sleep, patients need to change their lifestyle by exercising, losing weight, darkening their rooms, or cutting back on coffee.