The document describes the development of the Sleep Health Index (SHI) by the National Sleep Foundation to more rigorously measure sleep health trends in the U.S. population. The SHI uses data from national surveys to create sub-indices on sleep quality, duration, and disorders. Validation testing found the SHI has good reliability over time and that lower SHI scores correlate with poorer overall health, higher stress, and less life satisfaction. The SHI will now be calculated quarterly to track trends and relationships between sleep health, demographic factors, and health outcomes.

1. Presented at the annual meeting of the
American Association for Public Opinion Research
Austin, Texas
May 13, 2016
David Cloud, Kristen Knutson – National Sleep Foundation
Julie E. Phelan, Gary Langer – Langer Research Associates
The Sleep Health Index ™

2. A Brief History of Polling at
the National Sleep Foundation
Kristen Knutson, PhD

3. 3
The Sleep in America (SIA) Poll
• Started in 1990
• Released during Sleep Awareness Week
• Goal: To increase media and public awareness
of sleep

4. 4
The Sleep in America (SIA) Poll
• Surveyed sub-sections of Americans on sleep-
related topics (N~1000 respondents)
Year Topic Sample
2002 Sleep in Adults >18y
2003 Sleep in Older Adults 55-84 y
2004 Sleep in Kids <10 y
2006 Sleep in Adolescents 11-17 y
2007 Sleep in Women 18/-64 y; Women
2008 Sleep in Full-time workers >18 y & work ≥30 h/week
2010 Sleep & Race/Ethnicity 25-60 y; White, Black, Asian or
Hispanic
2011 Bedroom Environment 25-55 y
2012 Sleep & Transportation Workers Pilots, truck drivers, train
operators and bus, taxi & limo
drivers
2013 Sleep & Exercise 23-60 y

5. 5
SIA Poll Challenges
• Questionnaire Design
– Question wording, responses, recall
• Minimal disclosures of methodology
• Not representative samples (nonprobability
sampling)
• Polls cannot be compared to each other.
– Variability in sample, topic, task force.
– No trends can be detected
• Lack of systematic process for archiving poll
materials

6. 6
NSF Faces these Challenges
• Hired outside group to audit the Poll.
• Led to:
– Polling expert consultant
– Creation of SIA Poll Fellow
– Use AAPOR standards to disclose methodology
– Increase scientific rigor (e.g. probability-based
sampling)
– Archive materials including data files, press
releases, questionnaire and methods reports

7. 7
Sleep Health Index™ Overview
• Developed over the course of a year
• Involved input from many different perspectives
including sleep researchers, doctors, methodologists, and
pollsters
• Addressed the limitations of the Sleep in America Poll
– Probabilistic
– Same population
– Same questions
– Significantly shorter
• Surveys 1,000 Americans on a quarterly basis
• Track trends over the years and seasons
• Calculates a ‘Sleep Health Grade’

8. 8
Creating the Sleep Health Index
• Resources- SIA Poll Scholar, Consultants, Task Force
• Question development and refinement
• Cognitive testing
• Pre-testing
• Question refinement
• Years 1 and 2 of data collection
• Question refinement
• Index creation – Langer Research Associates

9. 9
Construction and Validation
of the Sleep Health Index
Julie Phelan, PhD

10. 10
Objective
• Create a robust, clear and concise tool to assess sleep health
• Use existing data from the two national surveys conducted
for the Foundation in 2014 and 2015
– random-sample landline and cellphone interviews
– 28 substantive questions about sleep
– 2,503 respondents
• Test the SHI’s reliability and validity

11. 11
Index Construction
• 14 of the 28 questions were selected on a conceptual and
empirical basis
• Factor analysis identified three distinct constructs related to
sleep health: sleep quality, sleep duration and sleep disorders
• Cronbach’s alphas confirmed the internal consistency of these
subindices: α= .63 to .77
• Virtually identical Cronbach’s alphas in 2014 and 2015 data
indicated reliability over time

12. 12
Sleep Quality Subindex
Simple average of scores assigned to six items:
• Self-assessed ratings of sleep quality
• Number of days in the past seven the respondent:
– had trouble falling asleep
– had trouble staying asleep
– was negatively impacted by lack of sleep
– dozed unintentionally
– felt well-rested (reverse coded)

13. 13
Disordered Sleep Subindex
Simple average of scores assigned to three items:
• Number in the past seven the respondent took a
sleep medication
• Whether or not the respondent reported having
a sleep disorder
• Whether or not the respondent has discussed
sleep problems with a doctor

14. 14
Sleep Duration Subindex
Simple average of scores assigned to three items:
• Weekday sleep score: how well self-reported
weekday time in bed aligns with expert
recommendations for optimal sleep
• Sleep deficit score: how well respondents’
approximate weekday sleep aligns with the amount
of sleep they say the need to feel their best
• Social jetlag score: how well respondents’ weekday
time in bed aligns with their weekend time in bed

15. 15
Sleep Health Index Scores
77
69
80 82
75
68
79 80
0
10
20
30
40
50
60
70
80
90
100
Sleep Health
Index
Sleep Quality
Subindex
Sleep Duration
Subindex
Disordered Sleep
Subindex
2015 2014

16. 16
Distribution of SHI Scores
24%
27%
19%
14%
17%
0%
10%
20%
30%
40%
50%
Grade: A
(90-100)
Grade: B
(80-89)
Grade: C
(70-79)
Grade: D
(60-69)
Grade: F
(<60)

17. 17
Sleep Quality (Score 68)
Excellent: 11%
Very good:
19%
Good: 35%
Fair: 22%
Poor: 12%
NET: 33% NET: 31%
Item score: 49

18. 18
Add’l Sleep Quality Items: Days in Past 7 Resp.
3.9
2.1
1.7 1.5 1.3
0
1
2
3
4
5
6
7
Felt
well-rested
Had trouble
staying asleep
Had trouble
falling asleep
Negatively
impacted by
lack of sleep
Dozed
unintentionally
55 69 76 78 82

19. 19
Disordered Sleep (Score 81)
0.8
0
1
2
3
4
5
6
7
Took sleep medication
# of days out of the past
seven…
89
15%
27%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
a diagnosed sleep
disorder
spoken with a
doctor about
sleep issues
85 69
% who have…

20. 20
Sleep Duration (Score 79)
5% 6%
15%
27%
25%
14%
9%
0%
10%
20%
30%
40%
50%
<5
hours
5 to <6
hours
6 to <7
hours
7 to <8
hours
8 to <9
hours
9 to <10
hours
10+
hours
Time in Bed
average: 7.7 hours
TIB score: 67

21. 21
Sleep Duration Deficit …and Social Jetlag
28% 29%
24%
20%
0%
10%
20%
30%
40%
50%
None <1 hr 1 to <2
hrs
2+ hrs
Score: 84
Average: 1.1 hours
51%
26%
22%
0%
10%
20%
30%
40%
50%
60%
70%
1 hr or
less
1 to <2 hrs 2+ hrs
Average: 1.1 hours
Score: 88

22. 22
Testing Construct Validity

23. 23
SHI by Overall Health
81
76 80
88
64
51
77
66
0
10
20
30
40
50
60
70
80
90
100
Sleep Health
Index
Sleep Quality
Subindex
Sleep Duration
Subindex
Disordered Sleep
Subindex
Excellent/very good health Fair/poor health

24. 24
SHI by Stress
67
54
73 74
81
77
82 84
0
10
20
30
40
50
60
70
80
90
100
Sleep Health
Index
Sleep Quality
Subindex
Sleep Duration
Subindex
Disordered Sleep
Subindex
Extremely/very stressed Only a little/not at all stressed

25. 25
SHI by Life Satisfaction
80
74
81 84
61
46
69 66
0
10
20
30
40
50
60
70
80
90
100
Sleep Health
Index
Sleep Quality
Subindex
Sleep Duration
Subindex
Disordered Sleep
Subindex
Extremely/very satisfied Only a little/not at all satisfied

26. 26
SHI by “How you’d use an extra hour”
67
56
71 74
78
71
80 82
0
10
20
30
40
50
60
70
80
90
100
Sleep Health
Index
Sleep Quality
Subindex
Sleep Duration
Subindex
Disordered Sleep
Subindex
Sleep Something else

27. 27
SHI by Mattress Comfort
77
70
80 82
65
53
73 72
0
10
20
30
40
50
60
70
80
90
100
Sleep Health
Index
Sleep Quality
Subindex
Sleep Duration
Subindex
Disordered Sleep
Subindex
Very/fairly comfortable mattress Not at all/not so comfortable mattress

28. 28
Sleep Quality by Sleep Disorders
56 57 54
71 73 71
0
10
20
30
40
50
60
70
80
90
100
Sleep disorder? Talk to doctor? Sleep medication?
Yes No

29. 29
Predicting the SHI
• Strongest predictors: stress and overall health
– Stress predicts all three subindices, sleep quality most strongly
– Health predicts sleep quality and disorders, not duration. (Poor
health is linked with sleeping too much or too little, hence a non-
linear relationship)
• Weaker predictors:
– Life satisfaction (predicts quality and duration, not disorder)
– Frequency of texting or emailing after initially falling asleep
(predicts quality and duration, not disorder
– Mattress comfort (predicts quality, not duration or disorder)
– Employment (predicts duration)
– Age (predicts disorder)

30. 30
Conclusions
• The Sleep Health Index demonstrates strong
empirical reliability and validity
• It provides a simple way to:
– summarize the nation’s sleep health overall and in three
separate but related elements - quality, duration and disorders
– track sleep health over time and across groups of interest
– assess the relationship between sleep health and key variables,
either asked alongside the index questions or – as time trend
develops – from external data sources
• Quarterly calculation of the SHI is now underway