I've taken Methylphenidate (Ritalin) from March 2014 to June 2015 on almost a daily basis (with a few breaks here and there) and I've taken it intermittently in August 2015.

I'm now not on Methylphenidate, but I still deal with a consequence of its use - Dopaminergic Hypersensitivity. Dopaminergic hypersensitivity means that dopamine receptors get supersensitive to dopamine molecules and they transmit a much stronger signal than they should have.

I was fine with Methylphenidate until one day, I decided to experiment with it and take a very low dosage. I took it, and the next time I've taken my regular dose I felt the effects were too strong and became hypersensitive to its effects. This happened on November 2014, a month after my concussion.

Now, even when I don't take Methylphenidate, I still feel like I'm on it. That means that I feel stimulated most of the day. That harms my sleep and alters my behavior - my average sleep time in the last 9.5 months (since I've taken the very low dose once) is 5 hours a night. I sleep only 5 hours a night - I fall asleep fine, but after about 5 or 5.5 hours, I wake up and feel my heart racing. I feel the adrenaline flowing and cannot go back to sleep.
I also have motor tics sometimes when I'm nervous and sleep deprived - this has never happened before I've taken the very low dose of Methylphenidate.

I'm sure that the hypersensitivity to dopamine has occurred because of the single very low dose of Methylphenidate I took - I read studies that monkeys given low doses of stimulants display permanent supersensitivity (lasting 28+ months) to the effects of the stimulants, suggesting their dopaminergic pathways have become more active and significantly more sensitive to input.

This condition is not improving. Unlike the PCS which I'm recovering from, the dopaminergic sensitization is persistent - in fact, it has only become worse after every time I took Methylphenidate. Sleep deprivation appeared first, motor tics (uncontrolled muscle movements) appeared later. I'm hypersensitive to Ritalin so it feels too strong for me. I'll soon start taking Adderall and am confident that it'll both solve this issue of hypersensitivity and treat my ADHD better than Ritalin.

Is this sleep deprivation detrimental to my recovery? It probably is, but is it significant? I'm also afraid that being sleep deprived (5 hours of sleep at night) for so long can cause brain damage by itself.