Good sleep helps our bodies produce Natural Killer (NK) cells which can kill pathogens like the COVID virus. Poor sleep does the opposite. People with poor sleep lack NK cells in number.
Nature is your body and its surrounding natural environment. Poor sleep keeps our bodies from performing its normal duties, such as repairing damaged cells, restoring our energy, and preventing harmful cells & toxins from accumulating in the body.
Good sleep alone is a cure to many ailments even our mental emotional.