Pet mice are nocturnal rodents, which means they are most active during the night and sleep during the day. They typically sleep for several short periods throughout the 24-hour cycle, totaling around 12-14 hours of sleep per day. It's important to provide a quiet and dimly lit environment during the day to ensure they can get adequate rest. Mice are known to be light sleepers, so sudden noises or disturbances may easily wake them up.