For sure they can do that, but I found that after a while of taking it on a regular basis (after around a month), that the grogginess subsided somewhat.

I usually take around 10-20 mg before bed and sometimes that much in the morning as well, especially when I am going through a rough patch.

When my spasticity is really bad, I have taken extra doses to get it under control. I take an extra 20 mg and then add 10 mg every hour or so, up to 60 mg/within a few hours; even though I know that I will be sedated, dizzy and that my body will be weak from taking that much.
It is a trade off at times like that. Less spastic cramping, means less pain, but then the day is shot in regards to doing anything.

How long have you been taking it?

LDN helped to take the edge off of my pain and improved cognition as well as muscle fatigue (Thanks Sally ).

Some people find that some antidepressants also help with pain, so you might ask your PCP about that too.

With love, Erika