Understanding ongoing energy depletion Persistent fatigue can be complex and may have more than one contributing factor. In Long COVID and CFS/ME, symptoms may be linked to post-viral changes , post-exertional symptom flare (often referred to as post-exertional malaise in CFS/ME) , and autonomic nervous system dysregulation . Within The Perrin Technique  framework, fatigue and related symptoms are also discussed in relation to lymphatic congestion  and reduced efficiency of d