z

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What’s my story ? z

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Well how did I get here?

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• Enjoyed science = med school!

High school

• Majored in Premed + Psychology

• Met Jim Smith (from Florida State University)

Bachelors - Penn State

• Fred Stephan and circadian rhythms

• Met Fred Turek from Northwestern

Masters - Psychobiology program at FSU

• Reproductive endocrinology of circadian rhythms

Doctorate Biology Northwestern -

• Sarah Winans Newman - neurobiology of male sex behavior REP program

Post Doc at University of Michigan

z Then a miracle occurred…..

David Earnest

(Former grad student at

Northwestern)

Joan Morell

Faculty member

at Rutgers

Lydia Don

Carlos

Cheryl Sisk

(Former grad

student at FSU)

Invites me to apply for job at Rutgers

Invites me for a talk at

Rochester

At Rochester

I meet

Invites

Joan Morrell for talk

at

Michigan State

Lydia does

Post doc

with…

Jill Schneider

(undergrad at FSU)

Invites me to apply

for a job at Lehigh

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Sex, ageing and clocks

Jennifer Swann

Professor, Lehigh University

Dept Biological Sciences

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My sleep wake

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

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His sleep wake

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12

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Are we so different?

How do your patterns look?

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Larks and Owls?

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Why melatonin?

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Melatonin exhibits a strong rhythm

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Melatonin profiles of Larks and Owls

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Temperature also shows a rhythm with a peak opposite to melatonin

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Sex difference in circadian markers

Women are advanced compared to men in:

DLM On = Dim Light Melatonin Onset

CBT = Core Body Temperature minimum

DLMO Off = Dim Light Melatonin Offset

Cain et al, J Biol Rhythms . 2010 August ; 25(4): 288–296.

z Sex differences decline with age

Roenneberg, etal Current Biology Vol 14 No 24 R1038

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What time is it?

How do you know this?

Why do you know this?

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All organisms keep time

Microorganisms

Insects

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All of your body keeps

time

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The rhythms do not show the same phase relationship

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What are circadian rhythms?

Circadian = circa+dian (about one day)

Endogenous - generated internally

Entrainable – synchronized to time cues

Zeitgebers: light, food, social cues

The SCN controls circadian rhythms

The suprachiasmatic

nucleus is the “Master

oscillator”.

Sits above the optic chiasm

and receives light from

special receptors in the

retina

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Why study rhythms?

Implications in health and disease

Travel – jet lag

Shift workers: health

professionals, airline pilots

Pathologies – DSPS, blindness

NASA!

z A hamster is housed

in a cage that

contains a running

wheel.

The running wheel

has a switch that

registers every

revolution of the

wheel and sends that

information to a

computer.

The computer puts a

time stamp on each

data point, and

collects the data over

long periods of time.

http://scienceblogs.com/clock/2006/07/clock_tutorial_4_on_methodolog.php

Hamster actograph

And circadian qualities

DD

D L

1. Light entrainment

2. “Free run”

persistence under

constant conditions

3. Period of free

running rhythm ≠24

hours

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z z Teenagers!

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z

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Seasonal affective disorder z

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Treatment depends on what type you are!

z

z

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z z Bright light treatment

resynchronizes rhythms

N Engl J Med 1990; 322:1253-1259

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Entrainment – life on mars

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Mars has a 24.69 hour day

Astronauts must adapt to the day length to

work with equipment

z z

Can astronauts adapt to 24.68 hour day?

Twenty subjects working in support of the Phoenix Mars Lander at the SOC in Tucson, AZ

Volunteered to work on a Mars schedule

Activity monitored with a wrist motion logger

Melatonin monitored via urine samples

From: Learning to Live on a Mars Day: Fatigue Countermeasures during the Phoenix Mars Lander

Mission Sleep. 2012;35(10):1423-1435. doi:10.5665/sleep.2128

Sleep | © 2012 Associated Professional Sleep Societies, LLC.

Yes they can!

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z In conclusion:

Circadian rhythms are

ubiquitous and important!

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Resources

https://neuron.illinois.edu/units/what-makes-me-tick-tock

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Thank you!