 Both drugs are reasonable well tolerated. However, efavirenz is known to cause mental side-effects. It is known that the initial use of EFV is associated with central nervous system CNS toxicity. The symptoms of such toxicity include daytime sleepiness, or alternatively inability to sleep, as well as vivid dreams including nightmares. The majority of such symptoms are believed to resolve within weeks; however there is controversy as to whether residual problems persist on a long term basis. Furthermore there are now reports of long time cognitive dysfunction associated with the use of efavirenz. Whether this is related to sleep disturbance is not clear. Studies to assess this impact have primarily involved assessment of sleep and cognitive function in antiretroviral ART-naïve subjects as they are initiated on first time ART that includes EFV. Such studies however are confounded by a return to health phenomena as HIV per se is known to cause sleep and cognitive deficits . There is controversy regarding whether use of efavirenz leads to long term disturbances in sleep and cognition. HIV per se causes sleep and cognitive deficits6 and studies which have tried to assess problems in antiretroviral-naïve subjects pre- and post- initiation of efavirenz-based regimens may be confounded by a return to health phenomena. 