Caffeine, Sleep and Attention:

Three things we would all like more of.

Blake Colyer&

Max Breidenstein

College students are deprived of sleep and heavy caffeine users (coffee, tea, energy drinks) which affects alertness

Attention and alertness are linked, so…

Background

To determine how sleep and caffeine effect attention levels in a college aged population

Along the way we will examine the possibility of a significant interaction because when tired, caffeine is a go-to for many students

Objective

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3 x 3 Factorial◦ Factor: Hours of Sleep (Fixed)

6 hours, 8 hours, 10 hours◦ Factor: Caffeine Consumption (Fixed)

0 mg, 95 mg, 190 mg 18 individuals randomly assigned to 9

treatment combinations◦ Experiment replicated 4 times

Experiment Design

Yijk = µ + αi + βj + (αβ)ij + eijk i=1,2,3 j=1,2,3 k=1,2

◦ µ = grand mean of attention◦ αi = fixed effect of hours of sleep

Σ αi =0 ,

◦ βj = fixed effect of caffeine consumption Σ βi =0

◦ (αβ)ij = fixed effect of interaction between sleep and caffeine Σ(αβ)ij =0

◦ eijk = experimental error eijk ~ NIID(0, σe2)

Statistical Model

Materials/Facilities◦ 18 homogeneous sleeping facilities

Sound proof rooms with bed◦ 18 Infrared gaze tracking units and computers

Machine that measures infrared reflection from cornea The more time spent viewing the screen, the greater

the attention to the task Wandering eyes mean a wandering mind

Procedure

http://www.tobii.com/en/about-tobii/what-is-eye-tracking/

Methods◦ Subjects arrive night before with staggered

bedtimes for common awakening hour of 8:00AM◦ Sleep, wake up, drink coffee 20 minutes later◦ Read short article whilst machine tracks eye

movement

Procedure (cont.)

Φ = √((rΣΣτij)/(abσ2)) Ho:τij=0 Ha:τij=1.5σ Φ = √((r4.5 σ2 )/(3*3 σ2)) Φ = √ (r / 2)

Power Analysis

r Φ Df2 = ab(r-1)

Power

5 1.58 36 0.76

6 1.73 45 0.823

7 1.87 54 0.925

8 2 63 0.95

Power = 0.90, α=0.05 The ideal replication size per treatment

combination to achieve the given power was 7. Considering we have 9 treatment combinations, that would imply needing 63 subjects in total. When being realistic about cost, it would make more sense to use 18 subjects and replicate the experiment 4 times

Power Analysis