Sleeping with earplugs can significantly improve the quality of your sleep. For many people, earplugs are the only way to block out sounds while they sleep, such as noise from a nearby freeway or a snoring partner.
This is significant because the quality of your sleep matters just as much as the amount you get. Loud sounds can wake you up out of a deep sleep. This has lasting effects, even if you wake up only for a few seconds. It takes time for your body to return to that phase of deep sleep that your body needs after a full day.