Inclusion Criteria:

• Females of childbearing potential who are sexually active must agree to use adequate contraception, and can neither be pregnant nor lactating from Screening throughout the duration of the study.
• History of nocturnal heartburn and GERD associated sleep disturbances prior to screening.
• Meets both of the following criteria: 1) nocturnal heartburn severity of moderate, severe, or very severe on at least 3 of 7 nights and; 2) GERD related sleep disturbances on at least 3 of 7 nights.
• Subjects must have history of symptomatic GERD prior to screening with GERD symptoms that were responsive to acid-suppressive therapy.

Exclusion Criteria:

• Erosive esophagitis visualized during the screening endoscopy.
• Allergy to any proton pump inhibitor drug (lansoprazole, omeprazole, rabeprazole, pantoprazole, esomeprazole), any component of Dexlansoprazole, or Gelusil/antacid.
• Active gastric or duodenal ulcers within 30 days prior to randomization.
• Upper gastrointestinal bleeding within 6 months prior to randomization.
• Co-existing diseases affecting the esophagus (eg, eosinophilic esophagitis, esophageal varices, scleroderma, viral or fungal infection, and/or Barrett's esophagus).
• History of radiation therapy or cryotherapy to the esophagus, caustic or physiochemical trauma such as sclerotherapy to the esophagus.
• Subject requiring dilation for esophageal strictures and/or strictures preventing passage of the endoscope during the screening endoscopy. Schatzki's ring (a ring of mucosal tissue near the lower esophageal sphincter) is acceptable.
• Has another condition that could be the primary cause of the subject's sleep disturbance.
• Evidence of uncontrolled, clinically significant neurologic, cardiovascular, pulmonary, hepatic, renal, metabolic, gastrointestinal, or endocrine disease or other abnormality (other than the disease being studied) which may impact the ability of the subject to participate or potentially confound the trial results.
• Diagnosis of cancer (except basal cell carcinoma) within 5 years of screening.
• Has a condition likely to require surgery during the study.
• Currently diagnosed with acquired immunodeficiency syndrome (AIDS).
• Abnormal clinical laboratory values.
• History of alcoholism or drug addiction.
• Subject who works the night shift.
• Subject who is planning to travel beyond 3 time zones during the study.
• Chronic use of non-steroidal anti-inflammatory drugs (NSAIDs), including COX 2 inhibitors within 30 days prior to randomization or anticipated use during the study.
• Use of the following medications during the 14 days prior to randomization or anticipated use during the study: proton pump inhibitors,sucralfate, misoprostol, corticosteroids, prokinetics, anticoagulant therapy, antiseizure medications (other than stable doses), psychotropic medications (other than stable doses), narcotic medications (occasional use allowed), bisphosphonates.
• Use of sleep medications, first generation antihistamines, benzodiazepines, modified cyclic antidepressants, antianxiety medications or drugs with significant anticholinergic effects such as tricyclic antidepressants or drugs with CNS effects that could mask perception of symptoms (eg, SSRIs, SNRIs). However, subjects who remain on a stable regimen and dose of these medications during the 90 days prior to randomization and who agree to maintain the same regimen and dose during the trial will qualify. Also, short term use of anticholinergics for trial related procedures is not exclusionary. Second generation antihistamines are not excluded.
• Use of histamine (H2) receptor antagonists or antacids (except for trial supplied Gelusil) during the screening period or anticipated use during the treatment period.