Seeing things that aren’t there is far more common than most people realize. Large population surveys find that roughly 12–13% of people report experiencing at least one visual or auditory hallucination in their lifetime, and some studies put the number even higher. “Visions” can range from harmless flashes of light as you drift off to sleep to vivid, fully formed images of people or animals that feel completely real. The cause depends heavily on when your visions happen, what they look like, and what else is going on with your health.
Visions While Falling Asleep or Waking Up
The single most common explanation for visions in otherwise healthy people is something called hypnagogic or hypnopompic hallucinations. These are brief, involuntary perceptual experiences that happen during the transition into sleep or in the first seconds to minutes after waking. Up to 70% of the general population experiences them at some point.
Visual phenomena make up about 86% of these episodes. They often look like kaleidoscopic geometric patterns, shapes, and light flashes, but they can also involve detailed, lifelike images of faces, people, animals, or entire scenes. Some people hear sounds too, like a doorbell, music, or someone calling their name (reported in 8–34% of cases). Others feel physical sensations: a sense of falling, floating, body distortions, or the unsettling feeling that someone else is in the room.
These visions happen because, during early sleep stages, your brain’s visual processing areas remain highly responsive to internal signals even though external sensory input is fading. Your perception gradually becomes more self-generated and less tied to the real world. Hypnopompic hallucinations, the ones that happen on waking, are usually continuations of a dream that briefly persist into consciousness. Neither type is a sign of mental illness. They’re simply a quirk of how the brain transitions between states of awareness, and they tend to be more frequent when you’re overtired or stressed.
Sleep Deprivation and Physical Stress
If you’ve been awake far longer than usual, visions may be your brain’s direct response to exhaustion. Research on prolonged wakefulness shows that perceptual changes begin developing after just one night without sleep, and vision is the most affected sense, with disturbances reported in 90% of sleep deprivation studies.
The progression follows a fairly predictable pattern. After roughly 24 hours awake, visual distortions appear first: objects may seem the wrong size, shape, or depth. Between 30 and 48 hours, these distortions give way to illusions (misidentifying ordinary objects) and then simple hallucinations like flashes or shapes. Beyond 48 hours, complex hallucinations can develop, involving recognizable figures or scenes. These symptoms resolve quickly once you sleep. Dehydration, extreme heat, and high stress can accelerate or intensify these effects.
Medications and Substances
A surprisingly wide range of medications can trigger visual hallucinations as a side effect. The most commonly implicated categories include blood pressure medications (particularly beta-blockers), drugs for Parkinson’s disease that boost dopamine activity, antiseizure medications, psychiatric medications, certain antibiotics (especially cephalosporins and sulfa drugs), and even some drugs used to treat bone density loss.
On the substance side, stimulants like cocaine and methamphetamine are strongly linked to visual hallucinations, especially at high doses or during prolonged use. Alcohol withdrawal is another major trigger. The hallucinations that accompany severe withdrawal (delirium tremens) are typically vivid and frightening. If your visions started around the same time you began a new medication or changed a dose, that connection is worth investigating with your prescriber.
Vision Loss and Charles Bonnet Syndrome
People who are losing their eyesight sometimes begin seeing elaborate, detailed images that aren’t real. This is called Charles Bonnet syndrome, and it works on the same principle as phantom limb pain. When the retina sends less and less information to the brain, whether from macular degeneration, glaucoma, diabetic eye disease, or optic nerve damage, the visual processing areas of the brain become hyperexcitable. Neurons that normally wait for incoming signals start firing on their own, and the brain interprets that spontaneous activity as real images.
The hallucinations in Charles Bonnet syndrome are often strikingly vivid: detailed figures, animals, patterns, or faces. Critically, the person experiencing them usually knows these images aren’t real. There’s no confusion, no disorientation, and no accompanying mental health condition. It’s purely a sensory phenomenon. If you have declining vision and have started seeing things, this is one of the more likely explanations, and it doesn’t mean anything is wrong with your mind.
Neurological Conditions
Several brain-related conditions produce visions through different mechanisms. Epilepsy is one: seizure activity in or near the brain’s visual processing centers can generate hallucinations during a seizure. Simple flashes, colors, or geometric shapes suggest activity in the primary visual area, while more complex images of people, scenes, or objects point to involvement of higher visual processing regions.
Migraine with aura is another common cause. The visual disturbances in migraine (zigzag lines, shimmering spots, blind spots) are technically not hallucinations but distortions caused by a wave of abnormal electrical activity spreading across the visual cortex. They typically last 20 to 60 minutes and are followed by a headache, though some people get the visual aura without any pain at all.
In Lewy body dementia and Parkinson’s disease, visual hallucinations are a hallmark symptom. These conditions involve damage to brain pathways that help process and recognize visual information. The hallucinations tend to be complex and well-formed: insects, people (sometimes familiar, sometimes strangers), animals, children, or miniature figures. They emerge as the disease progresses and disrupts the brain’s ability to distinguish between real visual input and internally generated images. The brain essentially assigns real-world significance to its own spontaneous activity.
Delirium and Acute Confusion
Delirium is a sudden, severe state of confusion caused by medical illness, infection, metabolic problems, surgery, or drug effects. Visual hallucinations are the most common type of hallucination in delirium. Unlike the visions described above, delirium-related hallucinations come with a noticeable drop in awareness, difficulty focusing or following a conversation, and rapid fluctuations between agitation and drowsiness. Delirium is a medical emergency that signals something is significantly wrong in the body, even if the underlying cause turns out to be treatable.
Mental Health Conditions
Visual hallucinations do occur in psychiatric conditions like schizophrenia, bipolar disorder, and severe depression with psychotic features, but they’re actually less common than auditory hallucinations in these diagnoses. When someone with schizophrenia hallucinates, they’re far more likely to hear voices than to see things. Visual hallucinations as the primary or sole symptom are more suggestive of a neurological, medical, or substance-related cause than a psychiatric one. That said, visual and auditory hallucinations can occur together in psychotic episodes, particularly during severe mania or deep depression.
When Visions Are an Emergency
Most causes of visions, especially the sleep-related kind, are not dangerous. But certain patterns warrant urgent medical attention. Seek emergency care if visions are accompanied by sudden confusion or an inability to speak coherently, if they’re rapidly getting worse, if you feel the urge to harm yourself or someone else, or if voices are telling you to act on violent thoughts. New-onset hallucinations in an older adult, especially with fluctuating alertness, suggest delirium and need same-day evaluation. Visions that start suddenly in someone with no history of them, particularly alongside fever, headache, or a recent medication change, also need prompt assessment to rule out treatable causes.