ONCE - Only Nocturnal Combination Evaluation of Antiretroviral-Experienced HIV 1 Infected Subjects Switching to Atripla

Inclusion Criteria: * Patient must have documented HIV 1 infection by Roche Amplicor (Version 1.5 Ultra sensitive) or equivalent assay - either at screening or previously documented in the patient's medical record. * Stable HAART regimen of efavirenz, emtricitabine and tenofovir DF for equal to or greater than 24 weeks prior to Screening and must be on their first HAART regimen. * Undetectable plasma HIV 1 RNA (less than 50 copies/mL) at Screening and greater than or equal to 12 weeks prior to Screening. * Greater than or equal to 18 years old. * Adequate renal function by: Estimated creatinine clearance greater than or equal to 60 mL/min according to the Cockcroft Gault formula * Hepatic transaminases (AST and ALT) less than or equal to 5 times upper limit of normal (ULN) * Total bilirubin less than or equal to 1.5 mg/dL * Adequate hematologic function (absolute neutrophil count greater than or equal to 1,000/mm3; platelets greater than or equal to 25,000/mm3; hemoglobin greater than or equal to 8.0 g/dL * Serum amylase less than or equal to 1.5 times ULN (subjects with serum amylase greater than 1.5 times ULN will remain eligible if serum lipase is less than or equal to 1.5 times ULN) * Negative serum pregnancy test (females of childbearing potential only i.e., not surgically sterile or at least two years post-menopausal) * Women of childbearing potential (WOCBP) must be willing to use two methods of contraception to avoid pregnancy throughout the study and for up to 12 weeks after the last dose of study drugs in such a manner that the risk of pregnancy is minimized. Subjects may choose two (a barrier and highly effective method) of the birth control methods listed below: Hormonal birth control drugs, Male or female condoms with or without spermicidal gels, Diaphragm cervical cap with or without spermicidal gels, Intrauterine device * Female subjects who utilize hormone contraceptive as one of their birth control methods must have used the same methods for at least three months prior to study dosing. * Female subjects who are postmenopausal for less than two years are required to have FSH greater than or equal to 40 mIU/mL. If the FSH is less than 40 mIU/mL, the subject must agree to use highly effective method of birth control (as described above) to participate in the study. * Male subjects who are sexually active must be willing to use effective barrier contraception (e.g., condom with spermicide) during heterosexual intercourse from screening through completion of the study and continuing for up to 12 weeks after the last dose of study drugs. * Life expectancy greater than or equal to 1 year. * The ability to understand and sign a written informed consent form, which must be obtained prior to initiation of study procedures. Exclusion Criteria: * Known hypersensitivity or toxicities to emtricitabine (FTC), tenofovir DF (TDF) or Truvada * Known hypersensitivity or toxicities to Sustiva * Have a history of resistance to any of the study agents at the time of screening (documented presence of resistance mutation(s) as defined by the IAS-USA 2007 Guidelines * A new AIDS-defining condition diagnosed within the 30 days prior to the Baseline visit. * Pregnant/lactating or breastfeeding females * Severe hepatic impairment (greater than 5 times upper limit of normal as defined by laboratory transaminases) or deemed clinically significant by investigator. * Any currently known clinical or laboratory parameter of GSI Grade 4. However asymptomatic grade 4 abnormalities will be permitted at the discretion of the investigator if deemed clinically appropriate (excluding AEs and laboratory parameters mentioned elsewhere in the inclusion/exclusion criteria). Abnormalities deemed insignificant by the investigator must be discussed with the sponsor prior to enrollment. * Receiving on-going therapy with any of the prohibited medications. Administration of any of the medications must be discontinued at least 30 days prior to the Baseline visit and for the duration of the study period. * Active, serious infections (other than HIV infection) requiring parenteral antibiotic therapy within 30 days prior to Screening visit. * Current acute illness or infection (e.g., opportunistic) - including an active AIDS defining condition within the previous six months. * Hepatitis B coinfection or Hepatitis C coinfection * Malignancy other than cutaneous Kaposi's sarcoma (KS) or basal cell carcinoma. Subjects with biopsy-confirmed cutaneous KS are eligible, but must not have received any systemic therapy for KS with 30 days of Baseline visit and are not anticipated to require systemic therapy during the study. * Prior history of renal or bone disease deemed significant by the investigator. * Subjects currently taking part in any other clinical trial using an investigational product, with the exception of studies where the treatment studied has been stopped for more than 1 month. * Evidence of alcohol and/or drug or substance abuse that in the judgment of the investigator would likely result in the patient being unreliable in fulfilling the conditions of the protocol. * History of psychological illness or conditions that in the judgment of the investigator might interfere with the patient's ability to understand the requirements of the study. * Any other clinical condition or prior therapy that, in the opinion of the investigator, would make the subject unsuitable for the study or unable to comply with the dosing requirements and cause the patient to be unable to complete the study protocol.