The purpose of this study is to investigate whether

1. pharmacologically enhanced naps will show increases in specific sleep stages
2. whether these sleep stages will produces specific increases on memory tests
3. whether older adults will benefit more than young adults from increased SWS or Stage 2 on subsequent declarative and motor memory tests.

• Drug: Sodium Oxybate
  2.5g Sodium Oxybate administered during nap
• Drug: Zolpidem
  5mg Zolpidem administered during nap
• Drug: placebo
  Placebo administered during nap

• Sodium Oxybate: Experimental
  2.5g Sodium Oxybate administered during nap
  Intervention: Drug: Sodium Oxybate
• Zolpidem: Experimental
  5mg Zolpidem administered during nap
  Intervention: Drug: Zolpidem
• Placebo: Placebo Comparator
  Intervention: Drug: placebo

Inclusion Criteria:

• English-speaking individuals, half men and half women, and between the ages of 60 and 75 years will be recruited. No ethnic group will be specifically excluded from study. All participants will be recruited from general San Diego Community. An education requirement of at least 12 years completed will be imposed, as education may affect performance on the cognitive task.

Exclusion Criteria:

• Not having a regular sleep-wake schedule (defined as not meeting criteria listed above and/or a Horne-Ostberg Morningness-Eveningness Questionnaire score not between 31-69)
• Having a sleep disorder (reported or detected on the questionnaires)
• Any personal or immediate family (i.e., first degree relative) history of diagnosed significant psychopathology
• Personal history of head injury with loss of consciousness greater than 15 minutes or seizures
• History of substance dependence
• Current use of any psychotropic medications
• Any cardiac, respiratory or other medical condition which may affect cerebral metabolism
• Given the nature of the stimulus and its presentation, anyone with non-correctable vision and audition impairments will also be excluded.