Sleep-dependent Learning in Aging

Inclusion Criteria: * Age 18-80 yrs * Healthy sleeper * No diagnosed sleep or neurodegenerative disorder Exclusion Criteria: 1. Past diagnosis of any sleep disorder or evidence of a sleep disorder as assessed by self-reported sleep quality assessments, a standardized diagnostic interview, and an acclimation night of polysomnography. Using acclimation-night polysomnography, participants will be excluded with an Apnea-Hypopnea Index \>15; a Period-Limb Movement in Sleep index of \>15/hr; sleep-onset latency \> 45 min (indicative of insomnia); or sleep efficiency \< 80% (see Edinger et al., Sleep, 2004). In cases in which questions arise regarding a participants' inclusion or sleep records, a practicing neurologist board-certified in sleep medicine will review the documentation. 2. Past diagnosis neurological illness or head injury 3. Reported average sleep per night \< 5 or \> 9 hrs 4. Current employment involving shift work or an inability to keep a regular sleep schedule during the week prior to testing 5. Current use of psychotropic, recreational drugs, or sleep-altering medications (sleep medications, cold medicines within the past week, clonidine, sympathomimetic stimulants) 6. Daily caffeine intake of \> 4 cups (coffee, tea, colas) 7. Weekly alcohol intake of \> 10 cups 8. Pregnancy or \< 12 months post-partum 9. History of bipolar disorder, mania, or current evidence of depression as measured by Beck Depression Inventory score \> 25 10. Abnormal sleep (e.g., shift work, travel across \>2 time zones within the past 3 months). 11. Diagnosis of any Axis I disorder, neurological illness or head injury (according to Demographic and Health History form); 12. Score indicative of cognitive dysfunction (subtest scores \< 40) 13. Beck Depression Scale score indicative of depression (\> 19). Additionally, individuals will be excluded from magnetic resonance imaging studies (Exps 1, 4) for: 1. Left handed or ambidextrous 2. Claustrophobia 3. Presence of metal (thoroughly screened via questionnaire and metal detector) 4. Pregnancy