Sufferers may cover themselves with long, protective clothing or carry a sun parasol when going outdoors during the daytime, or simply never go outdoors at all when the sun is out, depending on the severity of the fear. Since sufferers stay indoors more than non-sufferers, it will make them more prone to becoming vitamin D deficient, as well as depression caused by a combination of vitamin D deficiency, isolation and feelings of alienation from other people, and a continuously dark environment. However, a vitamin deficiency can be helped by taking vitamin D supplements or by consuming vitamin D fortified foods.

Phobias are classified as a type of anxiety disorder. There is often no discernible cause of phobia onset, though Rachman describes three possibilities: classical conditioning, vicarious acquisition and informational/instructional acquisition. Occasionally, they are triggered by negative events surrounding the phobic object or situation - in this case, perhaps severe sunburn.

The Pacific Health Center suggested that these people have been staying away from the sunlight because of the growing fears with skin cancer or blindness. This is not technically heliophobia, but simply an unfounded and illogical solution. Obsessive compulsive disorder, if it includes an intense fear of being harmfully affected by exposure to the sun or to bright lights, can also cause heliophobia. It should be noted that forms of heliophobia based on such irrational fears can cause the sufferer to eventually develop a fear of being in public or a fear of people in general by association, as a crippling fear of bright light can significantly limit the places a heliophobe can comfortably visit, as well as prevent that person from going outside during the daytime, when most other people are active.

Other medical conditions such as keratoconus (an eye disorder that results in extreme optic sensitivity to sunlight and bright lights), migraine which can be triggered by bright light, and porphyria cutanea tarda, which causes the skin to be overly sensitive to sunlight to the point of causing blisters, can result in heliophobia if the sufferer begins to associate pain and discomfort with bright lights.

Hemeralopia is known to occur in several ocular conditions. Cone dystrophy and achromatopsia, affecting the cones in the retina, and the anti-epileptic drug Trimethadione are typical causes. Adie's pupil which fails to constrict in response to light; Aniridia, which is absence of the iris; Albinism where the iris is defectively pigmented may also cause this. Central Cataracts, due to the lens clouding, disperses the light before it can reach the retina, is a common cause of hemeralopia and photoaversion in elderly. C.A.R (Cancer Associated Retinopathy) seen when certain cancers incite the production of deleterious antibodies against retinal components, may cause hemeralopia.

Another known cause is a rare genetic condition called Cohen Syndrome (aka Pepper Syndrome). Cohen syndrome is mostly characterized by obesity, mental retardation, and craniofacial dysmorphism due to genetic mutation at locus 8q22-23. Rarely it may have ocular complications such as hemeralopia, pigmentary chorioretinitis, optic atrophy or retinal/iris coloboma, having a serious effect on the person's vision.

Yet another cause of hemeralopia is uni- or bilateral postchiasmatic brain injury. This may also cause concomitant night blindness.

People with hemeralopia may benefit from sunglasses. Wherever possible, environmental illumination should be adjusted to comfortable level. Light-filtering lenses appear to help in people reporting photophobia.

Otherwise, treatment relies on identifying and treating any underlying disorder.

Patients may develop photophobia as a result of several different medical conditions, related to the eye or the nervous system. Photophobia can be caused by an increased response to light starting at any step in the visual system, such as:

- Too much light entering the eye. Too much light can enter the eye if it is damaged, such as with corneal abrasion and retinal damage, or if its pupil(s) is unable to normally constrict (seen with damage to the oculomotor nerve).

- Due to albinism, the lack of pigment in the colored part of the eyes (irises) makes them somewhat translucent. This means that the irises can't completely block light from entering the eye.

- Overstimulation of the photoreceptors in the retina

- Excessive electric impulses to the optic nerve

- Excessive response in the central nervous system

- Elevated trigeminal nerve tone (as it is sensory nerve to eye, elevated tone makes it over reactive). Elevated trigeminal tone causes elevated substance P which causes hypersensitivity. Often due to jaw misalignment.

Common causes of photophobia include migraine headaches, TMJ, cataracts, Sjogren's Syndrome, Mild Traumatic Brain Injury (MTBI), or severe ophthalmologic diseases such as uveitis or corneal abrasion. A more extensive list follows:

Neurological causes for photophobia include:

- Autism spectrum disorders

- Chiari malformation

- Occipital Neuralgia

- Dyslexia

- Encephalitis including Myalgic encephalomyelitis aka Chronic fatigue syndrome

- Meningitis

- Trigeminal disturbance causes central sensitization (hence, multiple other associated hypersensitivities. Causes can be bad bite, infected tooth, etc.

- Subarachnoid haemorrhage

- Tumor of the posterior cranial fossa