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% 40% 30% 7 hours or less 8 hours 9 hours or more 20% 10% 0% 1 2 3 6-11 years 12-14 years 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 2 h 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, activity activity activity activity, cortisone melatonin sleep? temperature? temperature No. of experiments >20 1 6 4 2 Age of peak delay 15 21 years 39 months 80 100 days 30 40 days unknown, but delay evident at 35 45 d Age of establishing menarche: menarche: cycles in vag. first ovulation: first ovulation: overt cyclicity in 12 13 years 30 33 months opening: 35 45 days 27 40 days females regular ovul: first ovul: 35 150 days reg. ovulation: 13 16 years 42 45 months 30 80 days Age of establishing 12-16 years n/a 60-120 days 45-65 days n/a spermatogenesis Gonadal dependent maybe unknown maybe maybe unknown [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, 2007-2008. 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.