I am no expert at the physical causes for this and I think you should rule out the physical causes for it first. Anaemia
does cause tiredness
, whatever be the cause.
If you have associated symptoms like low mood, not enjoying your usual things, loss of appetite, memory/concentration/sleep/attention problems than you MAY have depression
, but that would be down the list in the differential diagnosis in your case. But just wanted to make sure it is there :-)