It is safe to wear a tampon to bed as long as it is not worn for longer than 8 hours, states the Kotex website. A pad is an alternative to avoid wearing a tampon for this maximum time length. Tampons should be changed ideally every 4 to 6 hours, notes the Center for Young Women's Health.
Wearing a tampon for an extended length of time is a risk factor for toxic shock syndrome. Toxic shock syndrome is a rare infection that can be life-threatening in some cases. The Staphylococcus aureus bacteria is usually associated with this infection, but bacteria from group A Streptococcus can also lead to toxic shock syndrome, notes Mayo Clinic. Although this infection is linked with tampon use, there are other risks factors for it, such as skin burns or viral infections.