My sister is an Occupational Therapist and she recommended that I try a weighted blanket, both for general relaxation and for settling down my brain when I'm overstimulated. This thing really works. The first time I tried it I started to relax within minutes, and that is saying something, as I have a lot of difficulty relaxing. I've started using it when I'm overstimulated and it really seems to help with that too; after about 20 minutes under the weighted blanket I notice that my light and sound sensitivities start to diminish.

If you google "weighted blanket" you can find some places that sell them, though they tend to be pricey. If you can't afford a weighted blanket and have access to a quiet pool or hot tub, you may be able to achieve a similar effect. Even wrapping yourself tightly in heavy blankets will probably have some effect.

The light pressure exerted by the blanket or water has a calming effect on the nervous system. This is why swaddling babies helps to calm them down.

I am not saying that this is a cure-all or magic bullet--far from it. But it could potentially be a really helpful tool in managing PCS, especially if you have difficulty sleeping and/or get overstimulated easily.