The purpose of the study is to investigate the benefits of switching away from efavirenz (which patients are taking in combination with Kivexa® or as part of the combination pill, Atripla®) in patients with central nervous system side effects (such as insomnia {difficulty with sleeping}, bad dreams etc). The investigators in this study will investigate the effect of switching to a single tablet regimen (Eviplera®) containing tenofovir, emtricitabine and rilpivirine. If patients are currently taking Atripla, rilpivirine will be the only new component of the combination.