Why is sleep considered to be a characteristic of intelligence in the Bhag 3.26.30?

samsayo ‘tha viparyaso niscayah smrtir eva ca

svapa ity ucyate buddher laksanam vrttitah prthak

Doubt, misapprehension, correct apprehension, memory and sleep, as

determined by their different functions, are said to be the distinct

characteristics of intelligence.