sleep-dependent learning in aging

Conditions: Sleep

Summary: the specific objective of this proposed research is to understand whether deficits in sleep-dependent memory changes reflect age-related changes in sleep, memory, or both. the central hypothesis is that changes in both memory and sleep contribute to age-related changes in sleep-dependent memory processing. to this end, the investigators will investigate changes in learning following intervals of sleep (overnight and nap) and wake in young and older adults.

exp 1: using neuroimaging, the investigators will consider whether differences in brain areas engaged during memory encoding contribute to age-related changes in sleep-dependent memory consolidation for a word-pair learning task. exp 2: the investigators will examine the rate of memory decay between encoding and sleep using two probes of declarative memory (word-pair learning and visuo-spatial learning). exp 3: the investigators will provide additional opportunity for encoding of the word-pair and visuo-spatial learning tasks. exp 4: using neuroimaging, the investigators will examine neural engagement during encoding and performance following intervals of sleep and wake. exp 5: the investigators will examine the rate of decay of motor sequence learning. exp 6: the investigators will examine whether enhanced training ('overtraining') improves sleep-dependent memory consolidation for older adults.

Eligibility criteria:
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 \ 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