Sleep is regulated by two body
systems:
Circadian Biological Clock
The Clock-Dependent Process that Regulates
Alertness
Sleep/Wake Homeostasis
The Process that Balances Sleep and Wakefulness
Circadian Clock
Suprachiasmatic
nuclei
Thalmus
Hypothalmus
Retino-hypothalamic
tract
The internal
mechanism that
regulates when
we feel sleepy
and when we feel
alert
Resides in the
brain and is
affected by light
and dark and
other Zeitgebers
Chronopathology
Sleep duration on school nights by age group
70%
60%
50%
7 hours or less
40%
8 hours
9 hours or more
30%
20%
10%
0%
1
6-11
years
2
12-14
years
3
15-17
years
NSF 2014 Sleep in America ® Poll
Sleep in the Modern Family
Summary of Consequences
Psychosocial consequences
Poor work performance and absenteeism
Disruption of family life and interpersonal relationships
Impaired social interactions
Isolation and depression
Cognitive consequences
Reduced accuracy and mental flexibility
Loss of the ability to sustain attention
Medical co morbidity
Personal Safety / Public Safety
Gastroesophageal reflux disease
Depression
Increased risk of cancer ??
Two Process Model for Sleep
A delay in circadian phase has been observed
around the time of puberty in six mammalian
species
Species
human
rhesus monkey
degu
laboratory rat
laboratory mouse
Magnitude of delay
1–3 h
2h
3–5 h
1–4 h
1 h?
Sex difference
M>F
only females exam.
M>F
M>F
only females exam.
Rhythms delayed
sleep,
melatonin
activity
sleep?
activity
activity
temperature? temperature
activity, cortisone
No. of experiments
>20
1
6
2
Age of peak delay
15–21 years
39 months
80–100 days 30–40 days
Age of establishing
overt cyclicity in 12–13 years
females
menarche:
menarche:
30–33 months
regular ovul:
first ovul:
13–16 years
42–45 months
cycles in vag. first ovulation:
opening:
35–45 days
35–150 days
Age of establishing
spermatogenesis
12-16 years
n/a
60-120 days 45-65 days
n/a
Gonadal dependent
maybe
unknown
maybe
unknown
4
maybe
unknown, but delay
evident at 35–45 d
first ovulation:
27–40 days
reg. ovulation:
30–80 days
[Dev Neurosci 2009; 31-276-284]
Two Process Model for Sleep
Phase Delayed
16
4
Two broad categories of Insomnia
Difficulty initiating or maintaining
sleep (DIMS)
Each results in Excessive Daytime
Sleepiness (EDS)
DSM IV – TR:
Primary Insomnia
Difficulty initiating or maintaining
sleep, or nonrestorative sleep, for at
least 1 month.
Clinically significant distress or
impairment
Not accounted for by another sleep
disorder, mental disorder, medical
condition or substance use.
The above sleep difficulty occurs
despite adequate opportunity and
circumstances for sleep.
Sleep Disorders
Extrinsic Disorders (etiology develops from outside
the body)
 Insufficient sleep syndrome
 Environmental sleep disorder
 Altitude insomnia
 Adjustment sleep disorder
 Nocturnal eating/drinking syndrome
 Stimulant dependent disorder
J Clin Sleep Med. 2014 Oct 17. pii: jc-00129-14. [Epub ahead of print]
Adolescent Crash Rates and School Start Times in Two Central Virginia
Counties, 2009-2011: A Follow-up Study to a Southeastern Virginia Study, 20072008.
Vorona RD, Szklo-Coxe M, Lamichhane R, Ware JC, McNallen A, Leszczyszyn D.
Background and Objective:
Early high school start times (EHSST) may lead to sleep loss in adolescents ("teens"),
thus resulting in higher crash rates. (Vorona et al., 2011). In this study, we examined
two other adjacent Virginia counties for the two years subsequent to the abovementioned study. We again hypothesized that teens from jurisdictions with EHSST
(versus later) experience higher crash rates.
Methods:
Virginia Department of Motor Vehicles supplied de-identified aggregate data on
weekday crashes and time-of-day for 16-18 year old (teen) and adult drivers for school
years 2009-2010 and 2010-2011 in Henrico and Chesterfield Counties. Teen crash
rates for counties with early versus later school start-times were compared using twosample Z-tests and these compared to adult crash rates using pair-wise tests.
J Clin Sleep Med. 2014 Oct 17. pii: jc-00129-14. [Epub ahead of print]
Adolescent Crash Rates and School Start Times in Two Central Virginia Counties,
2009-2011: A Follow-up Study to a Southeastern Virginia Study, 2007-2008.
Vorona RD, Szklo-Coxe M, Lamichhane R, Ware JC, McNallen A, Leszczyszyn D.
Results:
Chesterfield teens manifested a statistically higher crash rate of 48.8/1,000 licensed
drivers versus Henrico’s 37.9/1,000 (p = 0.04) for 2009-2010.
For 2010-2011, CC 16-17 year old teens demonstrated a statistically significant higher
crash rate (53.2/1,000 versus 42.0/1,000), while for 16-18 teens a similar trend was
found, albeit nonsignificant (p = 0.09).
Crash peaks occurred 1 hour earlier in the morning and 2 hours earlier in the afternoon in
Chesterfield, consistent with commute times.
Post hoc analyses found significantly more run-off road crashes to the right (potentially
sleep-related) in Chesterfield teens.
Adult crash rates and traffic congestion did not differ between counties
Conclusions:
Higher teen crash rates occurred in jurisdictions with EHSST, as in our prior study.
This study contributes to and extends existing data on preventable teen crashes and high
school start times.
Seven Steps for Reducing EDS
1.Obtain sufficient sleep.
2.Regularize sleep wake schedules.
3.Sleep Hygiene: Avoid sleep fragmenting substances
such as caffeine, tobacco, alcohol. Have comfortable
bed / bedroom.
4.Address sleep disturbing medical problems (Asthma,
nocturia, pain, diabetes, etc.)
5.Obtain bright light exposure (blue light better).
6. Review medications.
7. Diagnose and treat sleep disorders.