Chronic Fatigue Syndrome has many causes and manifests differently for everyone. Whatever form it takes, the sufferer has a collection of symptoms. The symptoms are not the same for everyone and can vary from person to person both in type and severity. For this reason, it is often misdiagnosed and people suffer far longer than they need to.
For some it can be completely debilitating causing the sufferer to be totally bedridden. My case would probably be categorized as moderately severe where I had a short spell of being bedridden amidst the many years of very low energy.