So, ever since I was little I have had intense internal dialogue. Since I can remember so as early as the 1st grade. It was really bad and would keep me up all night. Which caused me to have really bad insomnia. I was always falling asleep and even daydreaming throughout school. I also have anxiety.
Anyways, I feel that its pretty normal to have some inner dialogue going on, when you are thinking about a situation or working out a problem in your head. And very rarely do I speak out loud when this happens. But, lately I have been hearing a voice that asks very random questions or says very random things. (Nothing bad just random) and my natural response is to reply or answer the question. This has happened now a few times in the past two weeks and has started to weird me out.
Also, I have started to see things out of the corner of my eye. Which I also feel is somewhat natural. Our eyes and minds playing tricks on us. But again it has increased in the past couple of weeks I keep thinking I'm seeing people whether its outside, inside, at work, or at home.
I'm not terrified, but as it has been increasing I started trying to find out possible causes, why things like this might happen and if i should be concerned?
Everyone gets upset when they hear an "internal dialogue" but for many, this is life. I have it too.
I am a believer in the theory of multiplicity, that our personality is made up of many parts and they can and do speak to you and have their own opinions. You might want to do some research on Internal Family Systems by Richard Schwartz....a leader in proposing this as the true form the personality takes.
As long as it's not telling you to do something bad and you feel compelled to do it, then you are okay. If that is what it starts t do, then seek some help to find out why. As long as we are functioning okay, the mind can do all sorts of things and it doesn't mean you have a problem.
Most of mental illnesses started to surface in late teens or early 20'. If you are in that age category, you might be experiencing mental illness. Also, terrible insomnia can not be ignored, particularly it occurs on daily basis. Besides, most of folks with mental illnesses have terrible insomnia issue.
Sounds to me like you've been having pyschotic or related issues that appear not yet be serious, .... but often without treatment/med., mental illnesses, particularly serious form of mental illness, such as Schizophrenia and Bipolar progress even within few months' period.
If it were me, I'd seek at least a Psycho-therapist working with psychiatrist, because he/she determines what form of mental illness you've been having. Afterwards, you need to see the pychiatrist who prescribes proper medication/meds. to alleviate the symptoms.
Hear Voices/Internal Dialogue and See things 
