If you are not getting good sleep, you may be having episodes of apnea (failure to breath properly). Upper neck injuries can disrupt the brain's signalling to breath. This delayed signalling can put you in a cycle of sleep apnea that starves your brain leaving you tired and groggy. It is hard to get a sleep study done for this Central Sleep Apnea. If you snore, you may have Obstructive Sleep Apnea.

I have to be very careful with sleep posture so as to not aggravate my upper neck causing Central Sleep Apnea. If I have a bad night of breathing, I experience stressful dreams.

Hope this helps.

My best to you.