Scientists test brain zapping during sleep to tweak brain waves

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Medically healthy (based on self-report and study team review) * U.S. citizen or holding permanent resident status * English-speaking (able to provide consent and complete questionnaires) Exclusion Criteria: * Any current or past history of neurological disorders or acquired neurological disease (e.g. stroke, traumatic brain injury), including intracranial lesions (including clinically significant findings identified in first MRI) * History of inpatient psychiatric hospitalization * History of head trauma resulting in prolonged loss of consciousness; or a history of greater than 3 grade I concussions * Current history of poorly controlled headaches including intractable or poorly controlled migraines * Any systemic illness or unstable medical condition that may cause a medical emergency in case of a provoked seizure (cardiac malformation, cardiac dysrhythmia, asthma, etc.) * History of seizures, diagnosis of epilepsy, history of abnormal (epileptiform) EEG, or family history of treatment resistant epilepsy except for a single seizure of benign etiology (e.g. febrile seizures) in the judgment of a board-certified neurologist * Possible pregnancy or plan to become pregnant in the next 6 months (self reported) * Any metal in the head * Any medical devices or implants (i.e. cardiac pacemaker, medication infusion pump, cochlear implant, vagal nerve stimulator) * Dental implants * Permanent retainers * Any hair braid, dreadlocks, hair pieces, or extensions which cannot be taken out before the study sessions * Any head coverings or headdress that participant feels uncomfortable removing for the purposes of study sessions * Any medication that may alter seizure threshold taken during the study i.e., ADHD stimulants (Adderall, amphetamine); Tricyclic/atypical antidepressants (amitriptyline, doxepine, imipramine, maprotiline, nortriptyline, bupropion); SSRIs (Escitalopram, Fluoxetine, Sertraline); Antipsychotics (chlorpromazine, clozapine), Bronchodilators (theophylline, aminophylline); Antibiotics (fluoroquinolones, imipenem, penicillin, cephalosporins, metronidazole, isoniazid); Antivirals (valacyclovir, ritonavir); OTC antihistamines (diphenhydramine, Benadryl) * Claustrophobia (a fear of small or closed places) * Back problems that would prevent lying flat for up to two hours * Regular night-shift work (second or third shift) * Sleep apnea or other sleep disorder (self-reported)