It stresses your eyes more when watching TV, particularly action movies for long hours at night. It could result dry eyes. When watching TV or other digital devices closely in a dark environment, your eyes have to constantly adjust to the different lighting. The inconsistent changing level of light makes your eyes work extra hard, your hormone maybe disrupted, too. Do keep a small lamp on to reduce eyestrain and headache from harsh light stimulation. Sufficient rest, exercise and good nutrition helps, too.