Headaches occur for a variety of reasons. Here are several examples of headache triggers and how they affect people. 

Stress and Headaches

The most common headache trigger is stress, which releases certain chemicals in the brain that cause vascular changes. Anxiety, worry, shock, depression, excitement, and mental fatigue can cause stress-induced headaches. Stress-related headaches, typically in a "hat-band" distribution, can accompany sleep disturbances.

Lowering stress through relaxation, psychotherapy, behavior modification, and antidepressant drugs (under the watch of a physician) can provide relief for stress headaches. 

Alcohol and Headaches

Alcohol can trigger headaches immediately or following prolonged periods of drinking. Ethanol, the key ingredient of alcohol, is a natural diuretic and causes the body to lose vital salt, vitamins, and minerals. Over-consumption of alcohol can cause dehydration and chemical imbalances in the body and brain, leading to headaches that last for hours to days. Migraine and cluster headache sufferers can be especially sensitive to alcohol, even in small amounts.

If you suffer from headaches, you should avoid alcohol because it can worsen headache symptoms.

Allergies and Headaches

If you have an allergy, your nasal or respiratory tissues will react by becoming inflamed, which can increase pressure on your sinuses. If you have frequent migraines, you may also have a sensitive nervous system that triggers attacks provoked by specific smells or lighting situations. You may get a migraine or other headache not because of something you are allergic to, but because that allergen places stress on your body, which can then cause a headache. Migraines can come from nasal congestion or sinus symptoms. If this happens, it is more helpful to treat the condition as a migraine, rather than as a sinus headache or sinus infection.

Caffeine and Headaches 

Caffeine can both help and hurt a headache. Sometimes a cup of coffee offers relief from a headache, but you should limit your daily use of caffeine. Caffeine is a very common ingredient in prescription and over-the-counter headache medicines because it helps the body absorb headache drugs more quickly, bringing faster relief. But overstimulation from caffeine can trigger headaches, as can the “rebound effect” when you “come down” from the energy boost of caffeine. 

Eyestrain and Headaches

Long hours looking at television, computers, tablets, cell phones, and video games can lead to exhaustion, lack of circulation, and eyestrain, which can cause headaches. Rarely is eyestrain the sole cause of headaches. If we suspect that eyestrain is a problem, we may recommend an ophthalmological exam.

To lessen the risk of headaches, take frequent short breaks, walk for a bit, and stretch your neck, arms, and back while watching TV or using the computer to aid circulation. If you feel headache or migraine symptoms developing, try closing your eyes and breathing deeply to relax.

Hormones and Headaches

Headaches related to hormonal imbalance typically affect women, due to fluctuations in estrogen levels. Few women experience headaches only with menses; often, hormones are just one of many migraine triggers. Estrogen levels drop around menstruation, causing migraine attacks in up to 60 percent of women who tend to have migraines. After menopause, most women experience fewer migraines. However, women taking hormone replacement therapy may not see a decrease in migraines.

Typically, migraine symptoms improve during pregnancy, though some women experience the onset of frequent migraines while pregnant. If you start having headaches, or experience a change in your headaches patterns during pregnancy, you should discuss this with your obstetrician to make sure there is not a more serious underlying cause. If you use any medications for migraine, including over-the-counter medication, during pregnancy, check with your obstetrician to make sure it is safe.

Hypertension and Headaches

High blood pressure can cause many health problems, like headaches, by increasing stress levels. Blood pressure usually has to be quite elevated, above 200/110, to cause headaches. Discuss your blood pressure and the issues surrounding it with a doctor to see if it could be contributing to your headaches.

Light Sensitivity and Headaches

During a headache or migraine, you may be very sensitive to light, especially bright and flashing ones. Research shows that slow, flickering lights are more irritating than rapid ones. To avoid headaches caused by flickering light, try using anti-glare screens on computer monitors and daylight spectrum florescent bulbs.

Smoking and Headaches

Smoking contributes to headaches for both smokers and nonsmokers. Nicotine, a substance found in tobacco, can trigger a migraine. Exposure to second-hand smoke can be a trigger for those with sensitivity and history of migraine. Smoking increases the risk of stroke in those with migraine. Smoking appears to affect cluster headaches, and quitting can help control attacks. If you experience migraines, you should quit smoking and avoid places with second-hand smoke.