If despite resting, eating well etc, you still feel really tired all the time, it’s a good idea to ask your GP to run a few blood tests – iron & ferritin levels, and thyroid, particularly. If you are found to have abnormal levels, these can often easily be rectified with diet and herbs. If your iron levels are low, a good liquid iron supplement is often better than tablets, which can sometimes cause constipation. I always recommend Floradix, which you can get in loads of health stores and pharmacies. If it’s fluctuating thyroid, seek herbal help from a qualified practitioner.