Yes it's as you mentioned, candida causes fatigue in every aspect.
Insomnia accompanied with candida are often caused by low body temperature which in term is caused by - you guessed it - fatigue, but the fatigue we're addressing here is thyroid deficiency (also called hypothyroid) caused by adrenal insufficiency.
When you have hypothyroid symptoms the thyroid gland is making the adrenal glands work 24h a day which is abnormal since in healthy state it's supposed to take only half the time or so.
So addressing adrenal and thyroid glands is worth an effort.
The most recommended over-the-counter remedies against deficiency in the adrenal glands are cortisol, C vitamin, pantothenic acid (Vitamin B5), pantethine, siberian ginseng and parsley just to name a few.
Some mention chlorofyll too, it's better to talk to a health expert about dosages.
B-Vitamins are good for the immune system, but just taking one sort doesn't make it, B-Vitamins work in teams so a B-complex is to suggest.
However i have no experience in treating adrenal glands but what made my body temperature improve was calcium and iodine, since dairy wasn't preferred i went after non-carbonated mineral water and a good mineral salt which held calcium and iodine.
Gradually i'm having good results.