​Why Does Watching Television or Using a Computer Late at Night

Multiple Choice

​Why does watching television or using a computer late at night sometimes interfere with sleep?

A) Those devices emit the type of light that resets the circadian rhythm.
B) ​Those devices emit ultrasonic vibrations that increase heart rate.
C) ​The excitement from using those devices increases production of steroid hormones.
D) ​The content of those devices causes dreams to start earlier than usual in the night.