As a sleep mask: They block out light when sleeping, especially during air travel, or for those who sleep during the day, given that shutting out light[1] allows the user to achieve a deeper level of sleep. They can also provide relief from claustrophobia for magnetic resonance imaging (MRI) patients. People with glaucoma should avoid using these.[citation needed] In children's games, such as Pin the Tail on the Donkey and when hitting a piñata.