How to Dilate or Shrink Your Pupils on Command

Quick Dilation Techniques

Imagine a dark room. Research in 2014 showed that people can sometimes dilate their pupils by imagining dark shapes or dark scenes. Think of those black bears assaulting a black campground at midnight, and your eyes may widen temporarily.

Focus on distant objects, or unfocus your eyes. Your pupils will get bigger as your eyes adjust to a further viewing distance. Another way to approach this is to suddenly unfocus your eyes, blurring your vision as much as you can. If you're doing this correctly, your eyes will feel very relaxed; if you start to see double, you've probably crossed your eyes and need to start over. With these techniques, you won't be able to observe your own eyes, so you'll need to record yourself or have a friend watch.

Face a darker part of the room. As you probably know, pupils grow to let in more light. If you aren't able to dim the surrounding lighting, you can still dilate your pupils by turning to face away from windows and light source.

Try tensing your stomach. Suck your stomach in and keep the muscles tight as you watch yourself in a mirror, to see whether your pupils increase. Some people can dilate their pupils in this way, although the underlying mechanism is unidentified. If you see no change after repeated tensing and bending, move on to a different technique.

Picture something that gives you an adrenaline rush. Your pupils can dilate dramatically when you are excited, or especially when sexually stimulated, due to the release of oxytocin and adrenaline. In addition to dilated pupils, these chemicals also causes your mind to race, muscles to tense up, and breathing to go faster. Through biofeedback, people can learn to "drive" their adrenaline levels up or down.

Powerful Dilation Techniques

Use allergy eye drops. Pick up some over-the-counter eye drops intended to be used to treat allergies. These can cause your eyes to become dilated. Be sure to read the instructions, and never use more drops than the label recommends.

Drink an espresso or take decongestants. Stimulants that work on the sympathetic nervous system can trigger your iris muscles to dilate your pupils. These include caffeine, ephedrine, pseudoephedrine, and phenylephrine. The last three are found in most over-the-counter decongestants.

Consider 5-HTP supplements. This is an over-the-counter drug you can find at pharmacies or anywhere that sells health supplements. While 5-HTP is generally safe, too high a dosage can cause dangerous effects from "serotonin syndrome." Stick within the recommended dosage, and avoid 5-HTP entirely if you are on LSD, cocaine, antidepressants, large B-vitamin doses, or other substances that increase serotonin levels.

Avoid other substances unless recommended by a doctor. Some prescription eye drops can dilate pupils, but have serious side effects that should be weighed by a doctor. If you are going through methadone treatment or have a medical condition that constricts your pupils, ask your doctor for advice on how to counteract this. Some recreational drugs cause dilated pupils as well. These are illegal in most areas, and can come with additional health risks if combined with other substances that cause dilated or constricted pupils.

Constricting Your Pupils

Look at a bright, natural light. Stare at a bright window for a couple seconds. This will cause your pupils to shrink immediately. If you're outside, step into a patch of sunlight, rather than staying in the shadows. While light bulbs will work as well, natural light is more effective. Never look directly at the sun, as this could damage your eyes.

Focus intently on something close to you. Your pupils will narrow as you change your focus to something in front of your face. You can start by closing one eye and placing your finger in front of the open one. With practice, you can learn to focus your eyes close even when there's nothing there.

Consider medication. There are a variety of medications used to constrict the pupil, but these are usually only available as a prescription, or even administered by the doctor only. Opiates constrict pupils, but most examples are illegal in most countries. They can also cause serious harm, especially when combined with other drugs that cause pupil constriction or dilation.