english: It's fashionable at the moment because what's been shown is that within the brain, a whole raft of genes have been shown to be turned on only during sleep, and those genes are associated with restoration and metabolic pathways.
non_english: Momentálne je to v móde, lebo bolo dokázané, že v mozgu sú niektoré skupiny génov zapnuté iba počas spánku a tieto gény sa spájajú s obnovou