The University of Maryland Medical Center has noted that kava kava, through its calming effects, promotes a relaxed state and is helpful in treating insomnia, anxiety and nervous disorders. Because kava kava helps treat nervous disorders, it is also thought to be very effective for people who have Essential Tremor. A word of caution, though, kava kava may be linked to liver damage with extensive use, so make sure you get a physician’s recommendation for this supplement.