Debra J. SKENE - European Sleep Research Society · Skene et al., PNAS, 2018. Pathways of...

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Age-related changes in circadian factors and light interventions in healthy and pathological human ageing

Debra J. SKENE

ChronobiologyUniversity of Surrey, Guildford, UK

d.skene@surrey.ac.uk

Metabolomics

• better understanding of circadian and sleep/wake regulation of metabolism

• Powerful tool to elucidate mechanisms linking sleep restriction, circadian misalignment and metabolic disturbances

- peripheral clock phase/function during circadian misalignment

- biomarkers to track sleep and circadian disruption; and monitor recovery

Age-related changes in circadian factors and light interventions in healthy and pathological human ageing

Debra J. SKENE

ChronobiologyUniversity of Surrey, Guildford, UK

2 process model

Borbély, A. A.Hum.Neurobiol., 1982Daan, S., Beersma, D. G. M. and Borbély, A.A. Am. J.Physiol., 1984

Human circadian timing system

Human circadian timing system Circadian rhythms Effect of ageing

Treatment strategies - melatonin, light - in ageing

Challenges Circadian rhythms and ageing research?

Only measure clock outputs (eg melatonin, rest/activity)

Confounded – field studies

Cross-sectional, rarely longitudinal

Older people - medication/mobility issues

Participant numbers7 care homes in south-east England

Total number of residents = 256

Not suitable = 125(49%)

Suitable = 131(51%)

No = 51(39%)

Yes = 80(61%)

Wearing AWL = 73(91%)

In analysis = 48(66%)

Hopkins, S. et al. Current Alz. Res 2017

Not a homogenous group n = 80

MobilityFully mobile 20% Walking stick 11%Walking frame 16%Wheelchair 53%

MMSE score 27 – 30, no impairment 13%21 – 26, mild 26%11 – 20, moderate 53%0 – 10, severe 8%

8 registered blind (2NLP; 6 LP) Hopkins, S. et al. Current Alz. Res 2017

Hourly activity counts mean ± SEMA + C = fully mobileB + D = wheelchairE = walking frame

24h activity profiles (7 days)

Challenges Circadian rhythms and ageing research?

Only measure clock outputs (eg melatonin, rest/activity)

Confounded – field studies

The suprachiasmaticnuclei (SCN) of the hypothalamus

Site of circadian oscillator

Courtesy of Dr Michael Hastings

The Clock in the Brain

24 48 72

Time (hours)

Welsh, Logothetis, Meister & Reppert, Nature 1995

Courtesy of Till Roenneberg

Retina-SCN-PVN-SCG-pineal pathway

SCN rhythmicity drives melatonin rhythmEntrained to 24 h by light/dark via the retina-RHT pathway

Stehle, J.H., et al. 2011

(Retina)-SCN-PVN-HPA axis

Courtesy of Andries Kalsbeek

(Retina)-SCN-PVN-ANS

Courtesy of Andries Kalsbeek

SCN-driven melatonin and cortisol rhythms in constant routine conditions

Gunn et al., 2016

males n = 14

Confounders

• Light/dark cycle • Sleep/wake cycle• Activity/exercise• Drugs• Food• Posture• Stress• Menstrual cycle?

Challenges in measurement

Diurnal versus circadian rhythms

Diurnal – exogenous and endogenousRhythms may be influenced, or even driven, by environmental cycles

Circadian – endogenous Rhythms driven by endogenous timing mechanisms (“clocks”)

persist in constant conditions

Early “Clock” Experiments

DAYTIMELeaves are open

NIGHT TIMELeaves are closed

Mimosa pudica

de Marian, 1729

the constant routine protocol

• Designed to remove/minimise effects of external environment and behaviour (e.g. sleep)

• No knowledge of clock time• Constant dim light• Semi-recumbent posture• Minimal social interaction• Regular (e.g. hourly) small

isocaloric snacks

Diurnal versus circadian rhythms

Human circadian rhythms - endogenously generated

persist in constant conditions

• Melatonin• Cortisol• Rectal temperature• Activity• Sleep• Mood• Performance

Circadian rhythms

Rajaratnam &Arendt 2001

melatonin

core body temp

subjective alertness

task performance

triacylglycerol

Czeisler & Klerman 1999 Recent Prog Horm Res 54:97-132

Constant routine protocol versusentrained diurnal sleep/wake

Melatonin as a reliable marker of circadian phase

• unaffected by:meals, stress, bathing, sleep

• dim light conditions (< 8 lux)• exclude drugs• control posture, exercise

1500 1700 1900 2100 2300 100 300 500 700 900 1100 1300 1500 1700

clock time (h)

acrophase (calculated peak time)

mid-range crossing

25% rise/fall

onset/offset

* ** *

duration

‘biological night’

Markers of the melatonin rhythmused to characterise the timing of the circadian clock

Arendt & Skene, Sleep Medicine Reviews (2005) 9:25-39

Benloucif et al., 2007

SCN extra-SCN brain oscillators peripheral clocks

• synchrony between different internal rhythms• synchrony between internal rhythms and external cycles e.g. for diurnal animals: sleep at night, visual function and metabolic responses optimal in the day

DiagnosisMeasures used to assess - human circadian timing system

- SCN-driven rhythms (melatonin, cortisol)

- Markers of peripheral clocks?

Human peripheral clocks

• Buccal tissue (Cajochen et al., 2006)

• Blood cells (Archer et al., 2008; O’Neill and Reddy, 2011; Ackermann et al., 2013)

• Skin fibroblasts (Brown et al., 2005; 2008)

• Hair follicles (Akashi et al., 2010)

• Adipose tissue (Otway et al., 2011)

• Skeletal muscle (van Moorsel et al., 2016)

SCN extra-SCN brain oscillators peripheral clocks

Markers of human peripheral clocks? Plasma metabolomeBlood cells, buccal tissue, skin fibroblasts, hair follicles, adipose tissue, muscle

Skene et al., PNAS, 2018

Effects of Prior Simulated Shift Work on Metabolite Rhythms (Examples)

Sphingolipid SM C20:2

24/27 (89%) had significantly shifted (reversed) rhythms

• Rhythms in most metabolites dissociated from the SCN pacemaker rhythm

• Vast majority aligning with the preceding sleep/wake and feeding/fasting cycles

• Metabolic profiling (metabolomics) in plasma may provide a window onto peripheral clocks and the biobehavioral factors orchestrating them

Conclusions

Pathways of peripheral clock entrainment

From Mohawk et al. Annu. Rev. Neurosci. 2012

Human circadian timing system

Human circadian timing system Circadian rhythms Effect of ageing

Possible causes of age-related changes in circadian system

PinealGland

SCN PVN SCG

Output pathway

melatonin temperature sleep/wake

Input pathway

cortisol

PinealGland

SCN PVN SCG

Output pathway

Input pathway

cortisol

1. Clock disturbance

2. Entrainment abnormalities

3. Insufficient zeitgebers (time cues)

Biological rhythms

Amplitude

Period Phase

Courtesy Ken Wright

phase angle

TCircadian Terminology

bedtime

Amplitude

12 16 20 24 4 8 12 16 20 24 4 8 12

Clock Hour

Age-related changes

1. Amplitude2. Period3. Phase 4. Phase angle of

entrainment5. Response to light

Duffy et al., Sleep Med. Clin. , 2016

Phase angle of entrainment = phase relationship between a circadian rhythm and the environmental signal entraining the rhythm (e.g. light-dark cycle; sleep onset)

PinealGland

SCN PVN SCG

Output pathway

Input pathway

cortisol

Reduced amplitude

Human SCN- reduced number of vasopressin neurons- reduced amplitude of rhythm

- alterations in the neural and temporal organization of the SCN

Hofman and Swaab, 1988; review 2006

Age-related changes in melatonin

- reduced melatonin amplitude

Plasma melatonin

Waldhauser et al., 1988

Urinary 6-sulphatoxymelatonin (aMT6s)

Bojkowski and Arendt, 1990

Skene et al., 1990

Pre- and postmenopausal women (n=160)

Skene et al., 1990

Pineal melatonin - human postmortem tissue

Melatonin in CSF

Liu et al., 1999

PinealGland

SCN PVN SCG

Output pathway

Input pathway

cortisol

Concretions, reduced sympathetic innervation, -receptor changes, reduced NAT

- reduced melatonin production/amplitude most studies (diurnal, entrained)

Zeitzer et al., 1999

65+ Elderly- disease and drug freeDim light, semi-recumbent, sleep deprived, isocaloric meals

Constant routine study

PinealGland

SCN PVN SCG

Output pathway

Input pathway

cortisol

Reduced amplitudePhase advance of circadian rhythms

Age-related change in circadian period?

Explain phase advance of circadian rhythmsi.e shorter period as age?

Forced desynchrony

Sighted

Czeisler et al., Science, 1999

= 24.18 0.02 h

n = 11 youngn = 13 old

Human circadian period ()

0 10 20 30 40 50 60 70 80

aMT6stau (h)

Age (yrs)

aMT6s Period and Age

r = -0.02n = 23

Skene et al., unpublished

Totally blind

Real life

1. decreased melatonin production - decline in amplitude

2. phase advance of melatonin rhythm

16-20 21-30 31-40 41-50 51-60 61-70 71-81 16-810

18 83 18 13 4 136 n

Earlier aMT6s peak time with ageing

English et al., unpublished

solid line - older group

Earlier wrt clock time

Later wrt to biological timei.e. sleep/darkness

Older compared to young adults

PinealGland

SCN PVN SCG

Output pathway

Input pathway

cortisol

Age-related changes in the eye

Adapted from Weale, 1988

pupil size

lens transmission

S-cones melanopsin RCGs

Lerman, 1980

25 years

91 years82 years70 years

60 years47 years

increased lens density reduced transmission of light

Age-related changes in the lens reduce transmittance of short wavelength blue light

Average spectral density of the lens (adapted from Pokorny et al., 1987)

380 420 460 500 540 580 620 660

Wavelength (nm)

20 yrs

60 yrs

80 yrs

20 yrs

60 yrs

80 yrs

Spectral sensitivity?

Arendt, 1995

23:00 23:30 0:00 0:30 1:00 1:30 2:00

Clock time (hours)

l)Suppression by short wavelength light

o 424 nm 16 W/cm2

O 472 nm 36 W/cm2

Thapan, Arendt & Skene, J Physiol, 535, 261-67, 2001

Spectral sensitivity of light-induced melatonin suppression

Melatonin suppression as a function of wavelength and irradiance

Photons/cm2/sec

548 nm£ 520 nm 496 nm 472 nml 456 nmn 424 nm

1E+11 1E+12 1E+13 1E+14 1E+15 5E+15

Thapan, Arendt & Skene, J Physiol, 535, 261-267, 2001

Effect on non-visual light responses?

Light-induced melatonin suppression

max 456 nm max 548 nm

1. A significantly reduced response to the short

wavelength light (456 nm) in the older group

2. No difference between age groups in response to

medium wavelength light (548 nm)

Hypotheses

2.5 20 yrs60 yrs80 yrs

380 420 460 500 540 580 620 660

20 yrs60 yrs80 yrs

Average spectral density of the lens (adapted from Pokorny et al., 1987)

Wavelength (nm)

20 yrs60 yrs80 yrs

Age-related changes in short wavelength blue light sensitivity

Reduced responsiveness in the elderly

Exp Gerontol 40, 237-242, 2005

Time: F = 4.68, p < 0.0001Age: F = 35.76, p < 0.0001

Increased alertness in young during and after blue (456 nm) light

morealert

Time from start of light (h)

alised

aselin

moresleep

young (n = 11)

older (n = 15)

Sletten et al., J. Biol. Rhythms, 2009

0 1 2 3 4 5 6 7

No effect of age on alertness during and after green (548 nm) light

Time: F = 4.84, p < 0.0001

Time from start of light (h)

alised

aselin

young (n = 11)

older (n = 10)morealert

moresleep

y0 1 2 3 4 5 6 7

Sletten et al., J. Biol. Rhythms, 2009

Conclusions

AGEING• Acute responses to blue light are impaired- melatonin suppression, alerting effect

• Phase advancing effects of blue light retained

• Acute and phase shifting responses: Differentially affected by age?

- Different photopigment contribution?- Different melanopsin RGCs (M1 and M2)?

Herljevic et al., 2005; Ackermann et al., 2009; Jud et al., 2009; Sletten et al., 2009

Age-related changes

1. Amplitude2. Period3. Phase 4. Phase angle of

entrainment5. Response to light

reducedshorter (faster)? Noearlier clock timesleep at earlier biological timereduced acute effectsphase shifting effects?

3. Insufficient zeitgebersocular light, ↓ melatonin signalling

PinealGland

SCN PVN SCG

Output pathway

Input pathway

cortisol

LIGHT MELATONIN

Phase shift circadian rhythms

Chronotherapy to hasten adaptation

Light Melatonin

• shifts circadian rhythmssleep timing

melatonin

temperature

cortisol

Management/Treatment of

Circadian Rhythm Sleep-wake Disorders

Increase zeitgeber strength

Increase circadian amplitude

Light Melatoninsupplementation

Age-related ocular changes

Reduced sensitivity to blue light**

Reduced environmental light exposure

- reduced mobility

- homes poorly lit

Older people require 3-5 times more light

**Herljevic et al., 2005; Jud et al., 2009; Sletten et al., 2009

Why light supplementation for older people?

Optimisation of lighting for the elderly

increase blue light content

increase longer wavelengths - enhance any M- and L-cone input- melanopsin photoreversal

Revell and Skene, 2009

Light treatment shown some benefits

- older demented patients Van Someren et al., 1997; Fetveit et al., 2003; Riemersma-van der Lek et al., 2008

Blue-enriched 17000 K lights

- office workers; living environments Francis et al., 2008; Viola et al., 2008; van Hoof et al., 2008; Vetter et al., 2011

Why light supplementation for older people?

Spectral compositionBlue-enriched white light Control white light high colour temperature low colour temperature 17000 K 4000 K

400 450 500 550 600 650 700

17000 K lights

4000 K lights

Wavelength (nm)

Effect of blue-enriched and control white light

on sleep quality and daytime alertness

in older people?

- in the community

- in care homes

EU FP6 Marie Curie RTNESRC New Dynamics of Ageing/Philips Lighting

Field studies

Baseline

Light exposureA or B

Washout period

Light exposureA or B

Washout period

light exposure A or B

Community study - skeleton photoperiods

Effect of blue-enriched and control white light

on sleep quality and daytime alertness

in older people?

- in the community

- in care homes

EU FP6 Marie Curie RTNESRC New Dynamics of Ageing/Philips Lighting

Field studies

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

Care home study - protocol

base line care home lights ~ 60 lux

17000 K light ~ 900 lux

4000 K light ~ 200 lux

wash out period care home lights ~ 60 lux

12-week study, randomised, crossover design September - April in 2008/2009 and 2009/2010

Aims• To increase light levels and light exposure in

older people

• To test if increasing light levels will affect sleep, activity, alertness and mood

Hypothesis

high intensity blue-enriched (17000 K, 900 lux) > control (4000 K, 200 lux)

Care room original light conditions

Dimly lit, not uniform59 ± 52 lux (mean ± SD, n = 20 rooms)

Indoor lighting measured weekly (lux meter), after sunsetIn direction of gaze (vertical plane)

Supplementing light in care homes

Care home #1, 4000 K lights Care home #8, 17000 K light

More uniform, higher light levels

4000 K 195 ± 31 lux17000 K894 ± 129 luxCare home 59 ± 52 lux

24 hour light profiles

17000 K vs washout

4000 K vs washout

17000 KWashout

4000 KWashout

0 4 8 12 16 20 240

1500 17kWO

Time (Hours)

0 4 8 12 16 20 240

1500 WO4K

Time (Hours)

Conclusions

Blue-enriched light supplementation - well tolerated - positive effects

reduced anxietyincreased daytime activityadvanced activity rhythm

- negative effects increased night-time activityreduced sleep efficiencyreduced sleep quality

Using Light: ChallengesControlled laboratory studies

practical real life situations?

Need more large, randomised, placebo controlled studies for light optimisation

Adapt to specific subjects groups e.g. older people (shiftworkers etc)

Caution with high intensity “activating” blue-enriched light

Melatonin• shifts circadian rhythms

sleep timing

melatonin

temperature• acute effects

lowers temperature

lowers alertness, transient sleepiness

improves sleep (mood, performance)

Time (h)

Melatonin

Meal17:00 19:00 21:00 23:00 01:00

Core body temperature

Alertness

Acute effects of 5mg melatonin

PlaceboSubjective Alertness

Rectal Temperature

Deacon et al., 1994

Melatonin as a “sleep aid”• Not a classical sedative hypnotic

Reduces sleep latency

Increases total sleep time?

Reduces night awakenings?

• Older adults with sleep problems• (Children with neurodevelopmental disorders

autism, ADHD)

reducing sleep onset latency

in primary insomnia (p = 0.002)

in delayed sleep phase syndrome (p < 0.0001)

regulating the sleep-wake patterns in blind patients compared with placebo.

Auld et al., Sleep Med Rev. 2017

Melatonin receptor agonists

TASIMELTEON – HETLIOZ®

Selective MT1/MT2 agonist

FDA approved for non-24 h S/W disorder

Vanda Pharmaceuticalsmelatonin

Takeda

Sleep-onset insomnia

Valdoxan ®

ServierMajor depressive disorder

Acknowledgements

LIGHTKavita Thapan Victoria RevellMirela HerljevicTracey SlettenHelen ThorneKatharina Lederle

MELATONINSteven LockleyLisa HackJosephine Arendt

Benita Middleton

Lloyd Morgan

Samantha Hopkins

Daniel Barrett

Katrin Ackermann

Shelagh Hampton

FOODSophie Wehrens

Cheryl Isherwood

Skevoulla Christou

Simon Archer

Michelle Gibbs

Jonathan Johnston

AcknowledgementsCurrent and recent funding EU Marie Curie RTN EU FP6 IP

Past fundingBHF, EU Biomed, EU FP5, MRC, Pfizer, Servier R & D, Wellcome Trust

STOCKGRAND LTDSTOCKGRAND LTD

ESRC New Dynamics of Ageing

Thank you

@debrajskene

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Debra J. SKENE - European Sleep Research Society · Skene et al., PNAS, 2018. Pathways of...

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