Sleep Loss and Temporal Memory Yvonne Harrison and James A. Horne Sleep Research Laboratory, Loughborough University, Leicestershire, U.K. - PowerPoint PPT Presentation

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Sleep Loss and Temporal Memory Yvonne Harrison and James A. Horne Sleep Research Laboratory, Loughborough University, Leicestershire, U.K.

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Title: Sleep Loss and Temporal Memory Yvonne Harrison and James A. Horne Sleep Research Laboratory, Loughborough University, Leicestershire, U.K.


1
Sleep Loss and Temporal Memory Yvonne Harrison
and James A. Horne Sleep Research Laboratory,
Loughborough University, Leicestershire, U.K.
  • By Neha Kakkar

2
Introduction
  • Observations that sleep deprivation affects
    temporal memory were first made around 50 years
    ago by Morris, Williams and Lubin.
  • Psychological tests sensitive to sleep
    deprivation have usually been administered to
    sleep deprived volunteers, previously well
    trained in the test procedures.
  • However, these tests are simple and
    straightforward, but by the time they are tested
    on the sleep deprived people , they become
    tedious boring.

3
  • In 1977, Wilkinson suggested that boredom may be
    the key to a tests sensitivity to sleep
    deprivation.
  • He emphasized the point that sleep deprivation
    reduces the non-specific arousal level of the
    body, but has no specific effects.
  • This study focuses on the more specific effects
    of sleep deprivation on temporal memory, rather
    than the non-specific arousal effects.

4
Design
  • Between subjects
  • 4 conditions
  • Control non-sleep deprived with placebo(Cp ,n10)
  • Control non-sleep deprived with caffeine (Cc,
    n10)
  • Sleep deprived with caffeine (SDc, n10)
  • Sleep deprived with placebo (SDp, n10)
  • 35hrs without sleep
  •  
  • Caffeine and placebo were given double blind.

5
Participants
  • N40 (20 females, 20 Males)
  • Mean Age23.4yrs
  • Volunteers were screened to exclude smokers,
    heavy drinkers and those with sleep or medical
    problems such as insomnia.
  • All were moderate consumers of caffeine (100mg
    400mg)
  • Normal range (lt10) of the Epworth Sleepiness Scale

6
  • Caffeine is not known to improve performance in
    alert, non-sleep deprived subjects undergoing
    short-duration tests.
  • Control groups allowed to check this.
  • 350mg Anhydrous caffeine dissolved in 200ml
    decaffeinated coffee given in a divided dose
  • (200mg1645, 150mg1845)
  • Placebo decaffeinated coffee only

7
Testing
  • Task was explained a day prior to the study but
    were not allowed to practice
  • All groups tested between 730 to 830
  • Temporal memory for faces task based on colour
    photographs of unfamiliar faces.
  • Two sets of photographs were presented with a
    delay of 5 min between the presentations
  • List A 12 faces
  • List B 12 faces

8
  • After both sets, another presentation of random
    48 faces including 24 previously presented faces.
  • - For each one, asked whether they had seen the
    photo before (recognition) and also if it was
    part of List A or B (recency)

9
Results
  • Two-way ANOVA (sleep condition x caffeine)
  • Three-way ANOVA (sleep condition x caffeine x
    accuracy)
  • Recognition
  • No significant effects of sleep condition
    F(1,36)0.16
  • No significant effects for caffeine F(1,36)
    0.46
  • No interaction F(1,36) 1.57

10
Results
  • Recency
  • Significant Main effect of sleep condition
  • F(1,36)25.62, plt.005
  • Significant interaction (sleep condition x
    caffeine interaction) F(1,36) 4.26, plt.05
  • No main effect of caffeine F(1,36) 0.74

11
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12
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13
Results
  • Accuracy
  • Significant main effect for accuracy
    F(1,72)16.7,plt.005
  • All groups were more confident about being
    correct when judging responses that were right
  • Significant effect for sleep condition ,
    F(1,72)13.63, plt.005
  • Sleep deprived participants were more confident
    than control about being correct for both right
    and wrong responses.
  • Sleep deprived individuals were significantly
    more confident when they were wrong.

14
Discussion
  • Improved alertness by caffeine is clearly
    evident.
  • SDc group was more alert than SDp group.
  • Sleep deprivation did not significantly affect
    the recognition of faces, it did produce
    significant impairment of the temporal memory
    (recency component List A or B)
  • This suggests that sleep deprivation was having a
    specific effect on temporal memory, other than
    simply through a generalized reduction in
    arousal.

15
Discussion
  • Even though caffeine resulted in reduction in
    sleep for SDc group, they still performed worse
    than both control groups.
  • Temporal memory component of this faces test
    seems to rely on the integrity of the PFC (Daum
    et. al, 1996)
  • Patients with damaged PFC are impaired at the
    recency aspect of the task rather than with the
    recognition component (Daum et. al, 1996).

16
Discussion
  • Whether or not the present findings indicate
    sleep deprivation affects the PFC is a matter of
    debate
  • It could be possible that the recognition
    component of the face test may simply be less
    difficult and demanding than the recency part for
    the sleep deprived individual.
  • Limitation no agreed way of measuring task
    difficulty
  • Other sleep deprivation studies using
    neuropsychological testing indicate that PFC
    maybe prone to impairment during sleep loss
    (Harrison Horne, 1996).

17
Conclusion
  • With present findings, , it may not be clear
    whether the effects of sleep deprivation relate
    to a general problem with source memory than more
    specifically to temporal memory.
  • To determine this, one would need to look at the
    other aspects of the encoding stage ex
    where, who, if and when.

18
  • Strengths
  • Very easy to read and understand
  • Good display of results
  • Weakness
  • Not much interpretation of the results, short
    discussion section
  • Further experiments
  • Use fMRI or PET scan to compare the brain
    activations of sleep deprived and control
    participants

19
QUESTIONS
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