Memory Consolidation in Pharmacologically Enhanced Naps
Condition: Sleep
Study type: Interventional

Summary: 
      This study will examine whether various drugs affecting sleep cycles can improve different
      kinds of memory.
    

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.
    

Intervention name(s): zolpidem; Placebo
Intervention type(s): Drug; Drug
Intervention description(s): Participants will receive one dose of 10 mg before each nap.; Participants will receive a dose of placebo before each nap.
Intervention MeSH terms: Zolpidem
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Health Services Research
Keywords: Nap; Pharmacology; Memory; Visual Learning; Verbal Memory; Motor Learning