The experience of hearing voices when no one is speaking is formally known as Auditory Verbal Hallucinations (AVH). This phenomenon involves the perception of speech or other sounds that seem real but originate internally. While often associated with severe mental health issues, hearing voices is a common experience, with estimates suggesting that between 5% and 28% of the general population will experience it. The presence of AVH does not automatically signify a disorder, but it indicates a complex process within the brain. Understanding why this happens involves looking at a spectrum of causes, ranging from temporary physiological states to underlying medical or psychiatric conditions.
Hearing Voices Without Mental Illness
Many instances of hearing voices are transient events linked to normal brain states or significant life experiences. A common example is hypnagogic or hypnopompic hallucinations, which occur during the transition into sleep or upon waking up. These are considered a normal part of the sleep cycle, where the mind weaves realistic sensory experiences before full consciousness is established. Up to 70% of people experience these sleep-related hallucinations at least once, and they are usually harmless.
Temporary physiological stress or extreme fatigue can also trigger auditory experiences. When the brain is sleep-deprived or under high levels of stress, its ability to filter internal thoughts can be compromised. This can lead to the externalization of the internal monologue, where thoughts are mistakenly perceived as coming from the outside world. Intense grief following the loss of a loved one is another context where hearing voices is documented.
During bereavement, it is not uncommon for an individual to momentarily hear the voice of the person who has passed away, often finding a comforting quality. Prolonged sensory deprivation or extreme isolation can also cause the brain to generate its own stimuli, including voices, as it attempts to compensate for the lack of external input. These non-pathological causes tend to resolve once the underlying situational or physiological trigger is removed.
Physical Health, Neurological, and Medication Triggers
Auditory hallucinations can stem from specific physical changes, chemical interactions, or structural issues affecting the brain. Certain prescription medications interfere with neurotransmitter systems, particularly those involving dopamine and serotonin, which can result in AVH as a side effect. Antidepressants, sedatives like zolpidem, and some antibiotics have been reported to trigger these experiences.
The sudden cessation of certain substances can induce a state of chemical imbalance that leads to hallucinations. Acute withdrawal from alcohol, benzodiazepines, or recreational drugs can cause delirium, a confused state where the brain generates false perceptions. High fevers or systemic infections can similarly lead to temporary delirium, which often includes auditory and visual hallucinations, particularly in older adults.
Neurological conditions that directly impact brain function represent another category of causes. Conditions such as epilepsy, especially when seizures affect the temporal lobe, can manifest as brief, formed auditory hallucinations. The AVH in these cases is a symptom of physical interference within the neural circuitry. Other causes include:
- Traumatic brain injury
- Strokes
- Brain tumors
- Lesions in the areas responsible for auditory processing
A distinct physiological cause involves the sensory system itself, such as hearing loss. When the brain is deprived of expected auditory input, it can spontaneously generate phantom sounds, much like phantom limb pain. This phenomenon, related to musical ear syndrome or tinnitus, can sometimes be experienced as complex sounds or voices, as the brain’s auditory cortex remains active without external stimulation.
Primary Mental Health Conditions
For many people, Auditory Verbal Hallucinations are a prominent symptom of a primary mental health condition, often signaling a disconnect from reality known as psychosis. Schizophrenia is the disorder most frequently associated with AVH, with approximately 75% of individuals experiencing them. In this context, the voices are perceived as distinct from the person’s own thoughts, often heard as externalized speech.
The characteristics of the voices in schizophrenia are often negative, critical, or commanding. They may involve a running commentary on the person’s actions or an argument between multiple voices. Neuroimaging studies suggest these experiences correlate with increased activity in the brain’s auditory networks, specifically the left superior temporal gyrus, which is involved in speech perception. This suggests the brain mistakes internally generated speech for external sounds.
AVH also occurs in other mood disorders, although they are often less frequent or intrusive than those seen in schizophrenia. Around 20% to 50% of people with Bipolar Disorder may experience voices, typically during severe manic or depressive episodes that include psychotic features. Approximately 10% of those with Major Depressive Disorder, especially severe cases, may also have auditory hallucinations, often with content that aligns with feelings of worthlessness or guilt.
Post-Traumatic Stress Disorder (PTSD) is another condition where AVH is reported, affecting up to 40% of individuals. These voices frequently relate directly to the traumatic events, such as hearing the voice of an abuser or sounds associated with a life-threatening moment. The experience is often tied to intrusive trauma memories rather than a general psychotic process. In psychosis, the individual is convinced the voices are real and external, contrasting with non-psychotic voices which are recognized as an internal phenomenon.
Knowing When to Get Help
The decision to seek professional help often rests on the nature, persistence, and impact of the voices on daily life. If the voices are mild, infrequent, and occur only when falling asleep or waking up, they are considered non-pathological and do not require immediate medical intervention. However, any new onset of AVH, especially when experienced while fully awake, warrants an assessment by a healthcare provider.
There are specific red flags that indicate a need for urgent professional evaluation:
- Voices that command the individual to harm themselves or others.
- Voices that are highly distressing, persistent, or overwhelming.
- A sudden increase in the frequency or intensity of the voices.
- Association with paranoia and a loss of touch with reality.
The initial medical assessment typically involves a primary care physician who will first work to rule out physical causes. This may include blood tests, a full neurological examination, and a review of all current medications and supplements. The goal is to identify and address any reversible physical or chemical triggers before considering a mental health diagnosis.
If physical causes are excluded, the next step involves a referral to a mental health professional for a comprehensive psychiatric evaluation. Early intervention is important, as many conditions associated with AVH, including psychotic disorders, respond well to prompt treatment. Talking openly and honestly about the nature and content of the voices is an important step in determining the appropriate path forward.