Evidence-Based Supplement & Herb Guides

Nocturnal Panic Attacks: Symptoms, Signs, Causes, and Risk Factors

Nocturnal panic attacks can cause sudden awakening with racing heart, air hunger, chest tightness, shaking, and intense fear. Learn how they differ from nightmares, sleep terrors, sleep apnea, seizures, and other conditions, plus when evaluation may matter.

Waking suddenly in intense fear can be disorienting, especially when it happens from sleep with no obvious warning. A nocturnal panic attack can feel...

Nihilistic Delusion Signs, Common Beliefs, and Related Conditions

Understand what nihilistic delusion means, how it differs from hopelessness or depersonalization, which symptoms may appear, and when urgent evaluation may be needed.

A nihilistic delusion is a fixed false belief that something essential has ceased to exist. It may involve the person’s body, identity, organs, mind,...

Nightmare Disorder Overview: Symptoms, Causes, and When Evaluation Matters

Learn what nightmare disorder is, how it differs from common nightmares and night terrors, what symptoms and risk factors matter, and when professional evaluation may be needed.

Nightmares are common, especially during stress, illness, poor sleep, or major life changes. Nightmare disorder is different. It involves repeated, disturbing dreams that are...

Night Terror Disorder: Symptoms, Signs, Causes, and Risk Factors

Learn what night terror disorder is, how sleep terrors differ from nightmares and seizures, what signs to watch for, and when nighttime episodes may need professional evaluation.

Night terror disorder involves repeated episodes of intense fear during sleep in which a person may scream, sit up, thrash, appear panicked, or seem...

Night Eating Syndrome Overview: Signs, Causes, and Diagnostic Context

A clear guide to night eating syndrome, including its symptoms, warning signs, possible causes, risk factors, complications, and how clinicians distinguish it from similar eating and sleep disorders.

Night eating syndrome is a pattern of eating and sleep disruption in which a person repeatedly eats a large share of their daily food...

Neurotic Depression Causes, Symptoms, and Conditions That Look Similar

Learn what neurotic depression means today, how it relates to chronic depression and dysthymia, and the symptoms, causes, risks, diagnostic context, and complications to watch for.

“Neurotic depression” is an older term that is still sometimes used in conversation, older medical records, and some international or historical psychiatric writing. In...

Neurosis Symptoms and Signs: What the Term Means in Mental Health

A clear guide to what neurosis means today, how it differs from modern mental health diagnoses, which symptoms and risk factors may be involved, and when evaluation may be important.

Neurosis is an older mental health term that many people still use to describe ongoing anxiety, worry, emotional distress, compulsive habits, or stress-related physical...

Neuropsychiatric Disorder Signs, Risk Factors, and Diagnostic Context

Neuropsychiatric disorder refers to symptoms where brain function and mental health overlap, including mood, cognition, behavior, perception, causes, risks, complications, and warning signs that may need evaluation.

A neuropsychiatric disorder is not one single diagnosis. It is a broad term used when changes in brain function are closely connected with changes...

Neuroleptic Malignant Syndrome Signs, Complications, and Urgent Red Flags

Learn what neuroleptic malignant syndrome is, how its symptoms and signs appear, which medication triggers and risk factors matter, and why urgent evaluation is important.

Neuroleptic malignant syndrome is a rare but serious drug reaction most often linked to antipsychotic medications and other medicines that reduce dopamine activity. It...

Neurodevelopmental Disorder Overview: Types, Signs, and Complications

Clear overview of neurodevelopmental disorders, including common types, early and later signs, possible causes, risk factors, diagnostic context, lookalikes, and complications.

Neurodevelopmental disorders are conditions that begin during brain development and affect how a person learns, communicates, moves, pays attention, behaves, or manages daily demands....

Neurocognitive Disorder Signs, Risk Factors, and Diagnostic Context

A clear guide to neurocognitive disorder, including mild and major forms, early symptoms, common causes, risk factors, diagnostic context, look-alike conditions, and complications.

Neurocognitive disorder is a clinical term for cognitive decline that is significant enough to be noticed, measured, and connected to changes in daily thinking...

Neurobehavioral Disorder Signs, Risk Factors, and Diagnostic Context

Neurobehavioral disorder can describe brain-related changes in behavior, thinking, emotion, self-control, and daily functioning. Learn key symptoms, causes, risk factors, complications, diagnostic context, and warning signs that need prompt evaluation.

A neurobehavioral disorder is a brain-related condition or clinical pattern in which changes in behavior, emotions, thinking, attention, self-control, social functioning, or daily living...

Neurasthenia and Persistent Fatigue: Key Symptoms and Complications

Learn what neurasthenia means today, including symptoms, signs, causes, risk factors, diagnostic context, related conditions, and warning signs that need evaluation.

Neurasthenia is an older diagnostic term for a pattern of persistent exhaustion, reduced mental or physical stamina, and distressing body symptoms such as headaches,...

Negative Symptom Schizophrenia: Overview of Core Symptoms and Functional Effects

Negative symptoms in schizophrenia can involve reduced motivation, speech, emotional expression, pleasure, and social interest. Learn how these signs differ from depression, positive symptoms, and cognitive changes, and when professional evaluation may matter.

Negative symptoms are among the most important but often least understood parts of schizophrenia. They describe a reduction or loss of normal emotional expression,...

Narcolepsy Overview: Symptoms, Cataplexy, Causes, and Risks

Learn what narcolepsy is, how its symptoms can appear, what causes and risk factors are known, which conditions can mimic it, and when professional evaluation may matter.

Narcolepsy is a chronic neurological sleep-wake disorder that causes the brain to have trouble regulating alertness, sleep, and rapid eye movement sleep. The result...

Narcissistic Personality Disorder Signs, Symptoms, and Clinical Features

A clear guide to narcissistic personality disorder, including core symptoms, grandiose and vulnerable signs, likely causes, diagnostic context, look-alike conditions, and possible complications.

Narcissistic personality disorder is a mental health condition involving a long-standing pattern of unstable self-esteem, exaggerated self-importance, need for admiration, and difficulty recognizing or...

Myxedema Psychosis and Severe Hypothyroidism: Symptoms, Risks, and Diagnostic Context

Learn how myxedema psychosis can occur with severe hypothyroidism, what symptoms and physical signs may appear, what it can be confused with, and when urgent evaluation may matter.

Myxedema psychosis is a rare psychiatric presentation of severe hypothyroidism, which means the body has too little thyroid hormone for normal brain and body...

Myoclonus Symptoms, Signs, Causes, Risk Factors, and Complications

Clear overview of myoclonus, including sudden jerks, twitching, positive and negative myoclonus, common causes, risk factors, complications, look-alike symptoms, and when evaluation may be urgent.

Myoclonus refers to sudden, brief, involuntary jerks or twitches of a muscle or group of muscles. Some forms are common and harmless, such as...

Mutism Explained: Types, Signs, Causes, and Risks

Learn what mutism means, how symptoms and signs can appear, what conditions may cause it, and when sudden or severe loss of speech needs professional evaluation.

Mutism means a person is not speaking, but the reason can vary widely. In some people, mutism is a pattern of not speaking in...

Muscle Dysmorphia Signs and How It Differs From Fitness Goals

A clear guide to muscle dysmorphia, including how it differs from fitness goals, the signs to watch for, common risk factors, possible complications, and when evaluation may be important.

Muscle dysmorphia is a mental health condition in which a person becomes intensely preoccupied with the idea that their body is too small, not...