Low dose naltrexone (LDN) is proposed to adjust the level of endorphins in the body thereby enhancing immune function and is anecdotally beneficial in MS. LDN is inexpensive, easily administered (one capsule a day at bedtime), and virtually has no serious side effect (during the first weeks of LDN use, some patients complain of some difficulty sleeping, that rarely persists after the first week). Although use of LDN is popular within the MS community efficacy is not proven because clinical trials have not been performed.