HIF1A and neoplasm: Hypoxia could (i) increase the expression of a transcription factor (HIF-1) involved in angiogenesis and resistance to therapy or (ii) modulate cells of the immune system, hindering anti-tumor responses and promoting some pro-tumors; or (iii) sleep disturbance could alter circadian rhythms, which are now known to be important for the expression of genes involved in cell proliferation and DNA repair.