An Open-Label Treatment With Randomization Observation, Investigator-Initiated Study, on the Duration and Efficacy of Jornay PM (Methylphenidate Hydrochloride Extended-Release Capsules) on Adult ADHD Symptoms and Executive Function and Emotional Regulation Throughout the Day Into Early Evening

Inclusion Criteria: 1. Adults ages 18-60 years, inclusive at the time of consent 2. Able to provide signed informed consent 3. Any gender 4. Subjects with a current primary Diagnostic and Statistical Manual of Mental Disorders (DSM) -5 diagnosis of ADHD of predominantly inattentive presentation, or combined presentations) as confirmed by the Adult ADHD Clinical Diagnostic Scale (ACDS) Version 1.2. 5. Subjects who are not receiving any pharmacological treatment for ADHD must have an DSM AISRS 18 item total score of ≥ 28 at screening. Subjects who were previously receiving pharmacological treatment for ADHD at screening must have a minimum total DSM AISRS 18 item score of ≥ 22 at screening 6. Dysthymia and anxiety disorders in remission, but stable on psychiatric medication for three weeks or more at the discretion of principal investigator will be allowed. Medication for these disorders to remain constant for the duration of the protocol. 7. Subjects, who have not used stimulant medication in the past 2 months. 8. Occasional use of marijuana (less than 3 times weekly) will be allowed during screening process until subject is enrolled into the study. After subject is enrolled onto Jornay PM, subject is asked to complete an attestation. The attestation will state that the subject will not consume marijuana while in the study. 9. No illicit substance will be allowed at screening or during the study. Exclusion Criteria: 1. Known hypersensitivity to methylphenidate, or product components. 2. Concurrent treatment with a monoamine oxidase inhibitor (MAOI), or use of an MAOI within the preceding 14 days. 3. Lifetime bipolar disorder, psychotic disorders, autism, intellectual disability except mood disorders accepted under the inclusion criteria at the discretion of the principal investigator. 4. Active suicidality within past year, or history of suicide attempt in past 2 years 5. Any history of severe past drug dependence determined by the Mini International Neuropsychiatric Interview (MINI) (i.e., a focus of clinical attention or a cause of substantial social or occupational difficulty) 6. Concurrent substance abuse and/or history of substance use within 6 months (except for marijuana use of less than three times a week and/or history of excessive marijuana use of less than three times a week within 6 months). 7. Use of any prescribed benzodiazepine 8. Any unstable medical or neurological condition; clinically significant medical abnormalities such as cardiovascular abnormalities, and any chronic condition of the central nervous system 9. Antidepressants and anti-anxiety agents (including benzodiazepines) taken in stable doses will be allowed, while other psychotropic medications, including hallucinogens, mood stabilizers, antipsychotics will not be allowed 10. Known nonresponse to MPH treatment 11. History of allergic reaction or sensitivity to MPH 12. Female of childbearing age, who are breastfeeding, pregnant, planning to be pregnant or men planning to make a woman pregnant during the study or for one-month post study 13. PI/clinician discretion