I get an overwhelmingly exhaustive/tired/dizzy/disoriented feeling when I'm in dark settings. In particular say a dark restaurant or lounge. This can be even during the day time.

When there is lots of light i have more energy.

I'm wondering if this is due to the fact I am significantly sleep deprived or that i have a vestibular issue?

Accident: 12 months PCS following severe fall resulting in severe concussion to right temporal region of brain. MRI/CT normal however they were taken 1-2 months after accident. Symptoms: Insomnia, Roaring Tinnitus in right ear only, fatigue, and disorientation/dizziness in dark settings

The right temporal/parietal area of the brain is closely associated with spatial orientation. Sounds like this is exacerbated when you are in dark environments, and it makes makes sense that you could become disoriented in those settings.

Regarding sleep deprevation, what do you mean? How much sleep on avearge do you get each night? If it's 7-8 hours I'm guessing that is not the root cause. Less than that it could be a contributing factor.

Are you seeing medical advice on your PCS symptoms?