Transcranial Magnetic Stimulation of the Default Mode Network to Improve Sleep

Inclusion Criteria: * Healthy men and non-pregnant, non-lactating women 18-50 (inclusive) years of age, free from contraindicated diseases, medications, devices, and conditions. * Participants must meet the criteria for primary insomnia as determined by scores on the ISI, PSQI, and ESS. Participants must obtain two out of three of the following required scores for each questionnaire: * Greater than or equal to 15 for ISI (Gagnon, Belanger, Ivers, \& Morin, 2013) * Greater than or equal to 6 for PSQI (Buysse et al 1989) * Greater than or equal to 11 for ESS (Johns, 2000) Exclusion Criteria: * Presence of any metal implant or medical device which may pose a safety risk for MRI or TMS (see below for examples) * Cardiac pacemakers * Metal clips on blood vessels (also called stents) * Artificial heart valves * Artificial arms, hands, legs, etc. * Brain stimulator devices * Implanted drug pumps * Ear implants * Eye implants or known metal fragments in eyes * Exposure to shrapnel or metal filings (wounded in military combat, sheet metal workers, welders, and others) * Other metallic surgical hardware in vital areas * Certain tattoos with metallic ink * Certain transdermal (skin) patches such as NicoDerm (nicotine for tobacco dependence), Transderm Scop (scopolamine for motion sickness), or Ortho Evra (birth control) * Past or present history of sleep or breathing-related disorders such as sleep apnea (exclusion upon obtaining a score of 3 or higher on the STOP-BANG questionnaire) * Travel outside the time zone within the two weeks prior to enrollment visit and at any point while active in the study * Self-reported major medical problems including past or present history of heart problems and/or neurological problems (to include but not limited to heart murmur, heart attack, TBI, stroke, tumor, epilepsy or another seizure disorder) * Self-reported past or present history of cardiovascular disease (to include but not limited to arrhythmias, valvular heart disease, congestive heart failure, history of sudden cardiac death or myocardial infarction) * Self-reported past or present history of neurological disorder (to include but not limited to traumatic brain injury including concussions, strokes, tumors, epilepsy or another seizure disorder, amnesia for any reason, hydrocephalus, multiple sclerosis) * Self-reported past or present history of any seizures or seizure disorders * Self-reported first-degree family history (like a mother, father, or sibling) of a seizure or seizure disorder * Self-reported underlying acute or chronic pulmonary disease requiring daily inhaler use * Self-reported history of fainting spells or syncope * Self-reported past (at any point in the participant's history) or present psychiatric problems not including depression and/or anxiety disorders (to include but not limited to bipolar, mania, ADHD, or psychotic disorders) * Self-reported history of depression and/or anxiety disorders within the past 2 years * Self-reported suicidal ideation as indicated by a score equal to or greater than 2 on the BDI * Self-reported current use of certain prescription medications including Ambien, benzodiazepines, stimulants (amphetamines, medication for narcolepsy), antidepressants (SSRIs, SNRIs), antipsychotics, blood pressure medications, thyroid medications. * Self-reported current use of supplements that may affect sleep (to include but not limited to melatonin, valerian root, kava root) * Self-reported caffeine use in excess of 300 mg (e.g., approximately 8 caffeinated sodas or approximately 3-4 12-oz cups of coffee) per day on average * Self-reported or suspected regular nicotine use (or addiction) (defined as more than 1 cigarette or equivalent per week within the last 1 year) * Self-reported or suspected heavy alcohol use (minimum limit to define heavy alcohol use is 14 drinks per week) * Self-reported or suspected use of illicit drugs (to include but not limited to benzodiazepines, amphetamines, cocaine, opioids) * (Females only) Positive urine pregnancy result (Urine HCG Test results) * (Females only) Self-reported or suspected current breast-feeding or collecting breast-milk * Learned English past age 3 * Speaking English as a non-primary language * Less than 9th grade education * Unusual sleep schedules in past six months * Overnight shift work * Inability to read and sign consent * Failure to cooperate with requirements of the study