I confirmed with our board-certified neurofeedback therapist (whom is also a psychologist) that screen time of any sort, whether it is video game, watching YouTube, Facebook, or even homeschool math lessons increases theta brain waves.
If theta is raised to a certain level then abnormal symptoms appear.
People with ADD / ADHD have high theta. If you guessed the abnormal symptoms of a neuro-typical person whose theta is raised due to screen time would mirror ADD you are right.
I have been told these things by my neurofeedback therapist. I am having trouble finding this data written in free articles on the Internet. Here is one source that duplicates the symptom list but I do not recommend using any machines to do neurofeedback at home which this same article talks about. This is a rapidly changing field as new technology comes on the market and as more information is gathered.
Here are some symptomsof abnormally high theta:
inability to focus
too many daydreams
depression
sleepiness
lack of excitement
extreme impulsiveness
hyperactivity
overly receptive mind
overly emotional state of mind
Elsewhere I read that listening to music increases theta. Since my son already has high theta waves I do not like that he has been sleeping with earbuds in with music on his iPod ALL NIGHT LONG.
In a conversation with our Connecticut behavioral optometrist in 2011 he told me that watching screens changes both our brain waves and our eye activity. He explained that starting at a screen changes our eye blinks and we stare rather than blink as normal. The eye staring mode changes brain waves that leads to the same symptoms that the neurofeedback therapist told me in 2012. The eye doctor also said that staring at small screens such as mobile phones or iPod Touch can hurt the eyes because the field of vision is limited and the eye muscles are not moving and scanning 180 degrees or looking at farther distances such as to scan the horizon for danger (what humans did for thousands of years). Our modern technology is shortening our eye focus and making our eye movements smaller. He especially cautioned against reading books on a mobile phone or on an iPod Touch, saying a book should be read on a normal page size. He cautioned against screen time before bed such as using eReaders and iPads or even TV. The eyes should wind down without screen time such as by reading a paper book and then going to sleep after having some non-screen viewing time.