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Memory Consolidation in Pharmacologically Enhanced Naps

This study has been completed.
National Institute of Mental Health (NIMH)
Information provided by (Responsible Party):
Lynelle A. Gehrke, University of California, San Diego Identifier:
First received: October 20, 2008
Last updated: December 8, 2015
Last verified: December 2015
This study will examine whether various drugs affecting sleep cycles can improve different kinds of memory.

Condition Intervention
Drug: Low-dose sodium oxybate
Drug: High-dose sodium oxybate
Drug: Low-dose zolpidem
Drug: High-dose zolpidem
Drug: Placebo

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
Primary Purpose: Health Services Research
Official Title: Understanding Memory Consolidation by Studying Pharmacologically Enhanced Naps.

Resource links provided by NLM:

Further study details as provided by University of California, San Diego:

Primary Outcome Measures:
  • Pharmacological enhancement of specific sleep parameters in a dose-dependent manner [ Time Frame: Measured at weekly study visits ]

Secondary Outcome Measures:
  • Correlation of pharmacological interventions with changes in sleep-stage-specific memory tasks [ Time Frame: Measured at weekly study visits ]

Enrollment: 30
Study Start Date: September 2008
Study Completion Date: September 2015
Primary Completion Date: September 2015 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Low-dose sodium oxybate Drug: Low-dose sodium oxybate
Participants will receive one dose of 2.5 g before each nap.
Experimental: High-dose sodium oxybate Drug: High-dose sodium oxybate
Participants will receive one dose of 3 g before each nap.
Experimental: Low-dose zolpidem Drug: Low-dose zolpidem
Participants will receive one dose of 5 mg before each nap.
Experimental: High-dose zolpidem Drug: High-dose zolpidem
Participants will receive one dose of 10 mg before each nap.
Placebo Comparator: Placebo Drug: Placebo
Participants will receive a dose of placebo before each nap.

Detailed Description:

Research provides evidence for strong, specific connections between sleeping and memory. This research shows that sleeping is necessary for certain types of memories to form, certain sleep stages lead to specific types of learning and memory consolidation, and naps are as effective as night-time sleep in these learning and memory processes. Current evidence also indicates that there are different types of memory and that the different types can operate and develop independently. In this study, three different memory types will be examined: perceptual, motor, and declarative memory. Perceptual memory is measured through the ability to recognize discrete stimuli; motor memory is measured through the ability to perform specific, coordinated tasks; and declarative memory is measured through the ability to recite memorized information. Different stages in the sleep cycle correlate with improvements in each of these memory processes. For instance, improvement of perceptual memory tasks is dependent on rapid eye motion (REM) sleep; motor learning is related to sleep stage 2; and declarative memory consolidation is related to short wave sleep (SWS), which includes sleep stages 3 and 4.

New drugs can target specific sleep stages and increase the amount of time people spend in those stages when they sleep. For example, the new prescription drug zolpidem increases time spent in stage 2 during sleep, and the drug sodium oxybate increases time spent in SWS. Compared to sleep impacted by either zolpidem or sodium oxybate, normal sleep has proportionally more time spent in REM. This study will use medications, or their lack, to manipulate how much time is spent in REM, stage 2, and SWS. The study will then examine whether the percentage of sleep spent in different stages affects the learning processes associated with those stages.

Participation in this study will last 6 weeks. At the outset, participants will undergo a 2-hour screening visit that will include a medical history, a physical examination, routine lab tests, urine tests for drugs and pregnancy, an electrocardiogram, and a clinical interview for mental health. Participants will also be asked to complete a series of questionnaires on subjective sleep quality, sleep quantity, and daytime sleepiness.

Participants will complete five study visits, beginning 1 week from screening and separated by 5 to 10 days to allow drug wash-out and recovery from effects of the previous visit. Each study visit will involve an overnight stay in a sleep lab. Participants will arrive at 8 PM, go to bed at 10 PM, and be awakened at 5 AM. Between 6 and 8 AM, they will undergo three different tests, each corresponding to a different type of learning and memory process: perceptual, motor, or declarative. The test will include recognizing a target image, typing a specific finger sequence on a keyboard, and verbally recalling a list of words. Participants will receive one of the study drugs or placebo at 8:30 AM and then be allowed to take a 90-minute nap between 9 and 11 AM. They will receive a different drug, different dosage, or placebo at each study visit. Between 4 and 6 PM, they will be retested on the previous three tests. While sleeping, participants will be outfitted with sensors monitoring muscle activity, eye movements, brain waves, heart and lung functioning, and—on the first night—breathing.

For the entire duration of the study, participants will wear an actigraph, which is a wristwatch-like device that monitors sleep cycles. Participants will also be required to maintain a regular sleep schedule, going to sleep and waking up in the same 2-hour window each day. They will also report on sleep schedule and caffeine, alcohol, and drug use in a daily sleep diary. Caffeine, alcohol, and drug use will be prohibited starting at noon on the day prior to each study visit.


Ages Eligible for Study:   18 Years to 39 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Speaks English
  • Resides in the general San Diego community
  • Completed at least 12 years of formal education, because education may affect performance on the cognitive task

Exclusion Criteria:

  • No regular sleep-wake schedule, defined as not meeting study criteria or scoring between 31 and 69 on the Horne-Ostberg Morningness-Eveningness Questionnaire
  • Presence of a sleep disorder reported or detected on the questionnaires
  • Personal or immediate family (i.e., first degree relative) history of diagnosed significant psychopathology
  • Personal history of head injury with loss of consciousness for more than 15 minutes or with seizures
  • History of substance dependence
  • Current use of any psychotropic medications
  • Any cardiac, respiratory, or other medical condition that may affect cerebral metabolism
  • Noncorrectable vision and audition impairments
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00777829

United States, California
UCSD General Clinical Research Center Laboratory for Sleep and Chronobiology (GCRC-LSC)
La Jolla, California, United States, 92093
Sponsors and Collaborators
University of California, San Diego
National Institute of Mental Health (NIMH)
Principal Investigator: Sara C. Mednick, PhD UCSD
  More Information

Responsible Party: Lynelle A. Gehrke, Administrator, University of California, San Diego Identifier: NCT00777829     History of Changes
Other Study ID Numbers: K01MH080992-01 ( US NIH Grant/Contract Award Number )
Study First Received: October 20, 2008
Last Updated: December 8, 2015

Keywords provided by University of California, San Diego:
Visual Learning
Verbal Memory
Motor Learning

Additional relevant MeSH terms:
Sodium Oxybate
Adjuvants, Anesthesia
Anesthetics, Intravenous
Anesthetics, General
Central Nervous System Depressants
Physiological Effects of Drugs
Hypnotics and Sedatives
GABA-A Receptor Agonists
GABA Agonists
GABA Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action processed this record on March 24, 2017