Caffeine is a popular way to help you wake up or stay up longer, but it may have negative side effects that can affect your vision. If you see zigzag flashing lights, you may have ingested too much caffeine, causing symptoms of an overdose. Stop consuming caffeine until you can be seen by your doctor.
Caffeine is naturally found in cocoa beans, coffee beans and tea and is synthetically produced for use in certain medications and in beverages. This substance is a stimulant drug that quickly enters the bloodstream and affects the brain. Caffeine helps to stimulate your mind and cause you to feel like you have more energy. However, its stimulant effects also can cause unpleasant side effects, including feeling jittery, anxious and unable to sleep. Caffeine is not intended for long-term use.