YWHAQ and cyclic hematopoiesis: These findings confirm the existence of a bidirectional link between CH and sleep disturbances in aged brains: ageing reduces the total time spent in deep sleep causing a decreased removal of waste products from the brain, included those involved in the development of CH; on the other hand, CH causes sleep fragmentation and the accumulation of molecules involved in different neurological diseases (e.g. β-amyloid, tau protein, pro-inflammatory cytokines) [24, 25, 100–103].