While watching too much TV or reading in the dark doesn't hurt your vision (that's just a myth), those activities may hurt your head. However, the link between the two may not be solely attributable to eyestrain.
Many of us log heavy hours sitting in front of the computer or television, often staying too long in the same position or even falling asleep while twisted into the contours and folds of the sofa.
A first line of defense is periodic movement -- stretch it out! Instead of demanding a family member bring you popcorn while you watch afternoon game shows, take the initiative during commercial breaks to rise up from your nest in the family room and journey into the kitchen to get your own popcorn. Now you're moving!
If you sit for long periods in an office chair at work (or in your home office), request or treat yourself to a more spine-friendly desk chair. If you do a lot of work on your computer, try to use screens with antiglare qualities. Even wearing tinted glasses during the day may prevent eyestrain headaches.
Finally, if you continue having headaches that seem related to eyestrain, see an eye specialist to make sure you don't have undiagnosed eye issues that are causing the problem. New eyeglasses or prescription lenses may just do the trick.
Next: a gender-specific headache type.