Week 6: Physical Activity, Sleep, and Cognitive Health

Question 1

What is the preclinical period?

Answer 1

The stage of disease where biomarker changes are observed, but they are not yet observable cognitive symptoms.

Question 2

What are the 4 stages of sleep called?

Answer 2

NREM Stages 1-3 and REM Sleep

Question 3

What is NREM Stage 1?

Answer 3

The transition period between wakefulness and sleep which lasts around 5 to 10 minutes.

Question 4

What is NREM Stage 2?

Answer 4

• When the body temperature drops and the heart rate begins to slow
• The brain also begins to produce sleep spindles
• Lasts around 20 minutes

Question 5

What is NREM Stage 3?

Answer 5

• Muscles relax and blood pressure and breathing rate drop
• Deepest sleep occurs

Question 6

What is REM Sleep?

Answer 6

• Brain becomes more active , body becomes relaxed and immobilised
• Dreams occur
• Eyes move rapidly

Question 7

List the objective measures of measuring sleep.

Answer 7

• Accelerometer based measures, e.g. FitBit - produces data about how long an individual’s spend either sleeping or doing physical activity
• Polysomnography (use EEG and other sensors to detect brain waves and movement throughout the night)

Question 8

How is sleep measured subjectively?

Answer 8

• Self-reported questionnaire

Question 9

List the aspects of sleep quality that are objectively-assessed.

Answer 9

• Sleep latency
• Sleep duration
• Sleep efficiency
• Wake after sleep onset
• Time spent in sleep stages

Question 10

List the aspects of sleep that are subjectively-assessed.

Answer 10

• Subjective sleep quality
• Sleep latency
• Sleep duration
• Sleep efficiency
• Sleep disturbances

Question 11

What is sleep latency?

Answer 11

How long it takes a person to fall asleep after they’re in bed.

Question 12

Give a few effects of sleep deprivation on cognition.

Answer 12

• Decline in working memory
• Impaired performance on attention-intensive tasks
• Increased incidence of microsleeps

Question 13

What is the most commonly examined metric of sleep quality?

Answer 13

Sleep duration

Question 14

How do we examine sleep and physical
activity together?

Answer 14

• Observe joint effects, each participant is categorised based on both their sleep and physical activity behaviours
• Isotemporal substitution methods: the effect on cognitive performance when a participant substitutes one movement behaviour for another
• Clinical trials: participants are assigned to receive a
  combination physical activity and sleeping intervention to see the effect on cognitive health

Question 15

How do we study sleep, physical activity,
and cognitive health?

Answer 15

• Cross-sectional studies (measure cognitive performance and prevalent dementia)
• Longitudinal studies (measure cognitive performance and decline and incident dementia)
• Clinical trials (measure cognitive performance or decline and incident dementia or reduction of dementia symptoms)

Question 16

What are the advantages of using cross-sectional studies to measure sleep, physical activity and cognitive performance at the same time?

Answer 16

Cheaper and straightforward analysis

Question 17

What are the disadvantages of using cross-sectional studies to measure sleep, physical activity and cognitive performance at the same time?

Answer 17

Not possible to establish temporality

Question 18

What are the advantages of using longitudinal studies to measure sleep, physical activity and cognitive performance at the same time?

Answer 18

• Can measure cognitive decline in addition to cognitive performance
• Able to establish direction of temporality
• Can examine incident dementia

Question 19

What are the disadvantages of using longitudinal studies to measure sleep, physical activity and cognitive performance at the same time?

Answer 19

Generally requires 10+ years of data to meaningfully examine cognitive decline or dementia