Grand jury is so named because traditionally it has greater number of jurors than trial jury, called a petit jury (from the French word petit meaning small).
Although mice tend to come out in the night when most of the occupants of the house are asleep or immobile. This allows them to stealthily infiltrate any of your food bags, crumbs etc. During the day time, mice will normally not come out, but if opportunities exist then they surely can.
Here are a few studies on the topic, and there's a good summary at [4]: Restricting mice to 4 or 5 hours sleep a night for just three nights caused the death of about 25% of locus ceruleus (LC) neurons in part of the brain stem.