Flashes of light (like a kaleidescope) in my peripheral vision followed by a headache?

What you are describing are classic symptoms of migraine headaches.....yours being what is called, "migraine with aura."

Many people with migrane headaches can predict when they will start as they have what are medically called, "scotomas" or "fortification spectra." They are described as being "lights" or rainbow of colors located at some periphery of vision that either grow or stay the same. These are often followed by the classic migraine headache.

Migraines often develop in young people, esp. in their 20s and 30s. It is not common for older persons to develop migraines unless they had them before.

You should go to a neurologist who will evaluate you and can prescribe some medications that will help you cope, if the headaches are incapacitating.

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This sounds like a Classic Migraine (also known as a Migraine With Aura).

"Classic migraines are characterized by 'auras', or neurological disturbances (most commonly visual disturbances), that occur in the period of 30-60 minutes before the migraine headache commences.

Typical aura symptoms include some of the following visual disturbances or visual hallucinations: flashes of bright light; zigzag lines; shimmering or haziness; double vision; dark spots before the eyes; and areas of lost or reduced vision."

In a non-doctor opinion, but as one who suffers from such symptoms, you have just described a migraine headache.

These happen when the levels of seretonin a chemical in your body changes.

The following website I found will be able to answer any other questions you have about migraines. There is even a list of things that can trigger migraines.

Migrane. That happened to me, I wasn't able to see a side of my mom, and my periheral vision was flashing. Then I had a headache later on, and I just drank tons, and I felt better!

Epileptic Seizure

This sounds like it could perhaps be a detaching retina, which is serious. You need to see an eye doctor soon. Be safe and always check with a doctor.

sounds like migraine though i'm puzzled about the half hour..