1. Thomas Hornick MD Patricia Higgins RN, PhD
Rest-Activity and Light Exposure Patterns in Older Adults: Methodological Implications
Thomas Hornick MD
Patricia Higgins RN, PhD

2. Objectives
Understand the influence of circadian rhythm disruptions on overall health.
Identify clinical characteristics of circadian rhythm disturbances in older adults
Recognize the importance of chronobiology in elders’ sleep-wake disturbances.
Describe results from preliminary studies assessing the use of circadian light therapy in a nursing home unit and measurement of circadian light exposure in a case study of home-dwelling older adults. 

3. Biological Rhythms Types of rhythms
Ultradian (heart beat, respirations, appetite)
Infradian (menstrual cycle)
Circannual (annual breeding cycles)
Circadian (sleep-wake cycle)
Rhythms allow organisms to time events and anticipate change!
Biological rhythms are periodic biologic fluctuations that correspond to, or are in response to, environmental change
Rhythms allow organisms to time events and anticipate change; i.e., rhythms allow organism to adapt to environmental change

4. Arendt 2006

5. With Zeitgeber

6. Disruption of circadian rhythm
Poor performance/fatigue (Reinberg et al, 2007, Laposky et al 2008)
Weight gain(Knutson et al, 2007)
Breast cancer (Stevens et al 2001)
Other conditions

7. Why older adults? Sleep disorders are common
Complaints among caregivers of persons with dementia frequently revolve around disordered day/night cycles
Medications for sleep are less safe in this population

8. Aging and light
Older adults spend much of their time in muted indoor lighting.
35 minutes/day of bright light exposure compared to approximately 58 minutes of bright light per day for middle-aged adults. (Sanchez 1993)
Reduced light exposure compounded due to physiologic changes
senile meiosis, cataract formation, and/or increased light absorption by the crystalline lens. (Charmin 2003)
Attenuation of light exposure by more than 80% in normal older adults relative to young adults.

9. Age related losses in retinal illumination
Turner et al Br J Ophthalmol November; 92(11): 1439–1444

10. Biological rhythms are endogenous but highly sensitive to environmental stimuli; i.e., light.
The influence of light and darkness on circadian rhythms and related physiology and behavior through the SCN in humans .
Wikipedia, accessed 10/30/09

11. Role of Retinal Receptors
Three known retinal receptors: process visual and circadian timing information
Rods and cones: visual data
Intrinsically photosensitive retinal ganglion cells (iPRGC): primarily light-dark data
process visual and circadian timing information

12. Spectral sensitivity of photopic, scotopic and circadian (melatonin suppression) photoreception
Spectral sensitivity of photopic, scotopic and circadian (melatonin suppression) photoreception.5 7 Peak sensitivities of circadian, scotopic and photopic photoreception are 460 nm (blue), 506 nm (green) and 555 nm (green-yellow), respectively. Spectral absorptance is shown for 30D blue blocking (AcrySof SN60AT, Alcon Laboratories, Fort Worth, TX) and UV-only blocking (ClariFlex, Advanced Medical Optics, Santa Ana, CA) intraocular lenses (IOLs).8 The area between the two IOL curves is the violet, blue and green light blocked in comparison with a UV-only blocking IOL.
Turner et al Br J Ophthalmol November; 92(11): 1439–1444

13. iPRGCs: History
1998: Melanopsin in light-sensitive cells on frog skin (Provencio et al, Proc Natl Acad Sci )
2000: Melanopsin-containing cells found in retinal ganglion cell layer (Provencio et al, J Neuroscience)
Most likely comprise the retinohypothalamic tract
Sensitive to wavelengths in the nm (blue light)
2002: Light responses from melanopsin-containing ganglion cells in humans (Berson et al, Science)
1998: Ignacio Provencio, U VA, first published article on melanopsin, photopigment in light-sensitive cells of frog skin. (Provencio I, Jiang G, De Grip WJ, Hayes WP, Rollag MD (January 1998). "Melanopsin: An opsin in melanophores, brain, and eye". Proc. Natl. Acad. Sci. U.S.A. 95 (1): 340–5. doi: /pnas PMID  )
2000: A novel human opsin in the inner retina. Provencio I, Rodriguez IR, Jiang G, Hayes WP, Moreira EF, Rollag MD. J Neurosci Jan 15;20(2):600-5.
2002: Don Berson, Brown University, (Berson DM, Dunn FA, Takao M (February 2002). "Phototransduction by retinal ganglion cells that set the circadian clock". Science 295 (5557): 1070–3. doi: /science PMID  )

14. Intrinsically photosensitive retinal ganglion cells (iPRGCs)
Timing Photoreceptors
Located throughout retina (~3000)
Express melanopsin
Blue light sensitive(peak 460nm)
Regulate photoperiodism (sensitivity to length of day and night)
Higher excitatory threshold than rods/cones
Transmits to SCN
24-hour light-dark pattern on the retina is the most efficient stimulus for entrainment of circadian rhythms in humans
ipRGC – intrinsically photosensitive retinal ganglion cells
Neurons: repeatedly fire electrical impulses: reset, fire, reset– light adaptation thought to occur during this process [possibly in the reset timing]
Photosensitive: Respond to contrast in light levels
Berson DM, Dunn FA, Takao M. Phototransduction by retinal ganglion cells that set the circadian clock. Science Feb 8;295(5557):
Melanopsin-containing cells found in monkey retinal ganglion cell layer (Provencio et al., 2000)
Most likely comprise the retinohypothalamic tract
Sensitive to wavelengths in the nm (blue light)

15. Suprachiasmatic nucleus (SCN) is master pacemaker
Activity in SCN correlates with circadian rhythms
Lesions of SCN abolish free-running rhythms
Isolated SCN continues to cycle
Transplanted SCN imparts rhythm of the donor on the host
SCN is known to be compromised in older adults with dementia. (Harper et al 2008)
SCN drives daily cycles of activity, hormones
SCN in humans have an intrinsic period slightly greater than 24 hours, and is modulated by the temporal pattern of light
and dark on the retina.
Disruption of this pattern leads from flying across times zones or from shift work can lead to sleep loss, weight gain or breast cancer ref
Stevens RG, Rea MS. Light in the built environment: potential role of circadian disruption in endocrine disruption and breast cancer. Cancer Causes Control. 2001;12:279–87. doi: /A: [PubMed] [Cross Ref]
Figueiro MG, Rea MS, Bullough JD. Does architectural lighting contribute to breast cancer? J Carcinog. 2006;5:20. doi: / [PMC free article] [PubMed] [Cross Ref]Lemmer B. Importance of circadian rhythms for regulation of the cardiovascular system: studies in animal and man. Conf Proc IEEE Eng Med Biol Soc. 2006;1:168–70. full_text. [PubMed]
Maemura K, Takeda N, Nagai R. Circadian rhythms in the CNS and peripheral clock disorders: role of the biological clock in cardiovascular diseases. J Pharmacol Sci. 2007;103:134–8. doi: /jphs.FMJ06003X2. [PubMed] [Cross Ref]Young ME, Bray MS. Potential role for peripheral circadian clock dyssynchrony in the pathogenesis of cardiovascular dysfunction. Sleep Med. 2007;8:656–67. doi: /j.sleep [PMC free article] [PubMed] [Cross Ref]Kreier F, Kalsbeek A, Sauerwein HP, Fliers E, Romijn JA, Buijs RM. "Diabetes of the elderly" and type 2 diabetes in younger patients: possible role of the biological clock. Exp Gerontol. 2007;42:22–7. doi: /j.exger [PubMed] [Cross Ref]Laposky AD, Bass J, Kohsaka A, Turek FW. Sleep and circadian rhythms: key components in the regulation of energy metabolism. FEBS Lett. 2008;582:142–51. doi: /j.febslet [PubMed] [Cross Ref]Knutson KL, Spiegel K, Penev P, Van Cauter E. The metabolic consequences of sleep deprivation. Sleep Med Rev. 2007;11:163–78. doi: /j.smrv [PMC free article] [PubMed] [Cross Ref]

16. Role of Melatonin Melatonin
Primary role in humans is to convey information about the daily light-dark cycle to physiological systems
Peaks during sleep, suppressed by light.
Melatonin is a methoxyindole synthesized and secreted principally by the pineal gland at night under normal environmental conditions. The endogenous rhythm of secretion is generated by the suprachiasmatic nuclei and entrained to the light/dark cycle. Light is able to either suppress or synchronize melatonin production according to the light schedule. The nycthohemeral rhythm of this hormone can be determined by repeated measurement of plasma or saliva melatonin or urine sulfatoxymelatonin, the main hepatic metabolite. The primary physiological function of melatonin, whose secretion adjusts to night length, is to convey information concerning the daily cycle of light and darkness to body physiology. This information is used for the organisation of functions, which respond to changes in the photoperiod such as the seasonal rhythms. Seasonal rhythmicity of physiological functions in humans related to possible alteration of the melatonin message remains, however, of limited evidence in temperate areas in field conditions. Also, the daily melatonin secretion, which is a very robust biochemical signal of night, can be used for the organisation of circadian rhythms. Although functions of this hormone in humans are mainly based on correlative observations, there is some evidence that melatonin stabilizes and strengthens coupling of circadian rhythms, especially of core temperature and sleep-wake rhythms. The circadian organisation of other physiological functions could depend on the melatonin signal, for instance immune, antioxidative defenses, hemostasis and glucose regulation. Since the regulating system of melatonin secretion is complex, following central and autonomic pathways, there are many pathophysiological situations where the melatonin secretion can be disturbed. The resulting alteration could increase predisposition to disease, add to the severity of symptoms or modify the course and outcome of the disorder.

17. Melatonin Rhythms and Aging
Average (±SEM) plasma melatonin in young (top, n=90) and older (bottom, n=29) subjects during a normally phased sleep episode (closed boxes) and a constant routine where they remained awake at the same clock hours (open circles). Data were aligned such that each subject's wake time was graphically adjusted to 08:00 and the data from the baseline day and night and from the CR(constant routine) expressed relative to wake time; sleep time is from 24:00 to 08:00. Melatonin data were averaged hourly within and then across subjects
Age , mean 68
Average (±SEM) plasma melatonin in young (top, n=90) and older (bottom, n=29) subjects during a normally phased sleep episode (closed boxes) and a constant routine where they remained awake at the same clock hours (open circles). Data were aligned such that each subject's wake time was graphically adjusted to 08:00 and the data from the baseline day and night and from the CR expressed relative to wake time; sleep time is from 24:00 to 08:00. Melatonin data were averaged hourly within and then across subjects.
Zeitzer et al Sleep November 1; 30(11): 1437–1443.

18. Plasma melatonin suppression by bright light in 65 year old man
Plasma melatonin data from subject 19G7, a 65 year old man who was exposed to a 3,527 lux light stimulus. Upper panel: plasma melatonin data from the initial circadian phase estimation procedure (CR1); middle panel: plasma melatonin data from the intervention day, with the 6.5-h experimental light exposure indicated by the open box; lower panel: plasma melatonin data from the final circadian phase estimation procedure (CR2) shown in the solid symbols, with data from CR1 replotted from above in the open symbols. During CR1, the fitted peak of the melatonin secretion (MELmax) occurred at 03:45, 3.5 h before habitual wake time. During CR2 MELmax occurred at 06:30, a 3.5 h phase delay. Melatonin was suppressed by 78% during the 6.5-h 3,527 lux light stimulus.
Plasma melatonin data from subject 19G7, a 65 year old man who was exposed to a 3,527 lux light stimulus. Upper panel: plasma melatonin data from the initial circadian phase estimation procedure (CR1); middle panel: plasma melatonin data from the intervention day, with the 6.5-h experimental light exposure indicated by the open box; lower panel: plasma melatonin data from the final circadian phase estimation procedure (CR2) shown in the solid symbols, with data from CR1 replotted from above in the open symbols. During CR1, the fitted peak of the melatonin secretion (MELmax) occurred at 03:45, 3.5 h before habitual wake time. During CR2 MELmax occurred at 06:30, a 3.5 h phase delay. Melatonin was suppressed by 78% during the 6.5-h 3,527 lux light stimulus.
Duffy et al Neurobiol Aging May; 28(5): 799–807.

19. Melatonin suppression with bright light
Phase shift of fitted plasma melatonin peak (MELmax) vs. illuminance of experimental light stimulus. Data from each of the ten subjects are plotted individually and shown with square symbols. Solid line represents the 4-parameter logistic model fit to the data, with the 95% confidence interval of the model shown in the dotted lines. For comparison, the 4-parameter logistic model fit to the data from our previous study in younger adults [64] is shown in the dashed line.
Phase shift of fitted plasma melatonin peak (MELmax) vs. illuminance of experimental light stimulus. Data from each of the ten subjects are plotted individually and shown with square symbols. Solid line represents the 4-parameter logistic model fit to the data, with the 95% confidence interval of the model shown in the dotted lines. For comparison, the 4-parameter logistic model fit to the data from our previous study in younger adults [64] is shown in the dashed line.
Duffy et al Neurobiol Aging May; 28(5): 799–807.

20. Circadian light transfer function
Figueiro, et al. 2006

21. Clinical applications

22. Light levels in contemporary and natural environments39 54–57 and also in phototherapy for seasonal affective disorder, which is typically 2500 lux for 2 h/day or 10 000 lux for 30 min/day.44 Illuminances are given in units of photopic lux. Photopic lux accurately describe the effectiveness of a particular light exposure for overall cone photoreception, which has a peak sensitivity at 555 nm in the green–yellow part of the spectrum (cf, fig 1). A standard circadian lux unit is needed10 40 but has not been adopted yet for comparing the effectiveness of different light exposures for circadian photoreception, which has peak sensitivity at 460 nm in the blue part of the spectrum (cf, fig 1).
Turner et al Br J Ophthalmol November; 92(11): 1439–1444

23. Therapeutic light 2 Hours bright light in AM
Improved sleep efficiency in NH residents
Fetveit et al, 2003
30 minutes sunlight for five days
Decreased napping
Increased participation
Alessi et al, 2005
Daytime bright light
Improved sleep/wake cycle in persons with dementia (van Someren et al,1997)
Studies using bright white light have demonstrated that light treatment can help reduce the negative impact of aging on circadian rhythms of sleep and wake, and thus, improve the quality and quantity of sleep in older adults, including those with dementia. Bright white light exposure in the morning improved sleep in institutionalized older adults. Fetveit et al12 demonstrated that exposure to 2 hours of bright light in the morning for at least 2 weeks substantially improved sleep efficiency of older adults living in nursing homes. Alessi et al.11 showed that five consecutive days of 30-minute exposure to sunlight, increased physical activity, structured bedtime and control of light and noise at night resulted in a significant decrease in daytime sleeping in intervention participants compared to controls. Further, they showed that intervention participants had increased participation in social and physical activities as well as social conversation. Murphy and Campbell49 have shown that light exposure in the evening can delay the circadian clock and help older adults sleep better at night and be more awake during the day.

24. Riemersma-van de Lek et al JAMA 2008
6/12 Homes randomized for lighting intervention
Installed fluorescent fixtures, both real and sham
1000 lux horizontal at eyes in intervention
Caregivers unaware which arm randomized to
Melatonin randomized by patient
3.5 year follow up
Light exposure was manipulated by
installing a large number of ceilingmounted
fixtures with Plexiglas diffusers
containing an equal amount of Philips
TLD 840 and 940 fluorescent tubes
(Philips Lighting BV, Eindhoven, the
Netherlands) in the common living
room. Lights were on daily between approximately
9 AM and 6 PM. The aim was
an exposure of ±1000 lux, measured
before the eyes in the gaze direction. This
intensity is technically feasible and has
in previous studies been confirmed
to synchronize circadian rhythms in
healthy people in temporal isolation31
and to improve circadian activity rhythm
disturbances in elderly patients with
moderate to severe dementia.32

25. MMSE, Depression
ADLs improved Less irritability, less inability to sleep in those with the lighting.
5%without decelerating the progressive cognitive worsening (as is also the case foracetylcholinesteraseinhibitors8).Light also reduced depressive symptoms by a relative 19% and attenuated the gradual increase in functional limitationsby53%.
A similar increase in efficacy over time by 2% was found fo
Riemersma-van der Lek, R. F. et al. JAMA 2008;299:

26. Schedule change: Shift work
Light at night (LAN)
Nurses’ Health Study (Willet, PI)
Effects of Light at Night on Circadian System in Nurses (Schernhammer, PI, RO1-OH008171)
30 year study
Evaluate light exposure in rotating shift workers based on the recent information on the specific wavelengths that affect melatonin levels in humans, and will relate those measures to the response of their circadian system, as measured by melatonin levels in urine. Specifically, we will measure light exposure by applying a new device, a circadian light meter that captures the short wavelength portion of visible light, which has been described to most strongly suppress melatonin levels and phase shift the circadian pace maker as part of the light's influence on non-image forming function in humans. Urine collections will be conducted during three of the overall 7 days of study period.
Sample 180
Approx 15 million shift workers in US: self selecting nurses, safety officers

27. Circadian phase shifters
Can have negative effects on health
Abrupt: jet lag, shift work
Gradual: institutionalization
Timed light exposure: reset clock
Sensitivity age-related
Bright light in morning advances the clock
Bright light in evening delays the clock
Delays easier than advances
Jet lag: Adjusting to new schedule can cause daytime sleepiness, insomnia, irritability, stomach upset

28. Circadian Lighting in Long-term Care: A feasibility study

29. Methods 3 participants, residents of Ward 62B
Lighting: GE fluorescent ceiling lamps 14,000 K
Instruments
Sleepwatch-L© (AMI, Ardsley, NY)
Neuropsychiatric Inventory-Nursing Home Version
DaysimeterTM (Lighting Research Center, Rensselear Polytechnic Institute) 29

30. Methods/Instrumentation for Sleep/Light Data
Subject wore Sleep Watch-L© for 7 days
Wrist-worn electronic measure of body movement and light
Software calculates activity/inactivity and light
© Ambulatory Monitoring Inc

32. Lighting Installation
VAMC safety standards
1st phase: 3 ‘blue lamp’ prototypes by GE: 8000 Kelvin (K); 14,000K;16,000K
2nd: 13 standard fluorescent lighting ceiling light fixtures in Dayroom
7 of 13 changed to 14,000 K ( K)
Timer controlled blue lighting on, 8a-6p
Lighting after 6pm: sufficient for visual acuity
Regular lighting is 5000 Kelvin (color correlated temperature, hot body radiation)

34. Mean of light measurements taken at eye level (horizontally) at 8 points in the room in the 4 cardinal directions, using PMA 2200 Photoradiometer, SnP Meter Photopic SL , S/N 9829
Light Conditions
Photopic (cones) Lux
Scotopic (rods)
Lux
S/P
Ratio
Brightness
Visual Effectiveness
all on
517
1178
2.24
781
1818
14,000 K only
381
918
2.26
606
759
standard
333
725
2.14
491
609
all off
222
489
2.17
328
412
Lux – SI unit of illuminance [human brightness perception] as measured by a light meter
1 lux = 1 lumen/square meter
Two types of photoreceptors: Rods/cones ratio = ~10/1
Photopic - brightness perceived by cones
Scotopic – brightness perceived by rods [more sensitive to bluish-white light]
Historically, light meters measured eye’s cone sensitivity to lamps/lighting = photopic data
More accurate measure combines the two [rods and cones] into a measure that more reflects what the human eye perceives in terms of light  S/P ratio
Studies indicate that lighting that provides higher S/P ratio provides better visual acuity
Visual effectiveness: “a measure of how the appearance of information and the use of visual elements within it affect the ease with which users can find, understand, and use the information. Because most… users use their eyes to access your information, the visual impact of that information can be an important factor in its general quality.”

35. Results & Conclusions Wrist actigraph well accepted
Light sensor on wrist covered much of the time by clothing?
New blue lighting well received
3 subjects exposure to blue lighting (time in Dayroom/ 10 hr period):
77 minutes, 371 mins, 373 mins
Next time: Change installation pattern?, use DaysimeterTM

36. Rest-Activity and Light Exposure Patterns in the Home Setting: A Methodological Study
P. Higgins, T. Hornick, M. Figueiro
American J Alzheimer’s Disease and Other Dementias, 2010

37. Purpose
Assess the feasibility and reliability of using a circadian light meter (DaysimeterTM) in a field setting and use the human circadian phototransduction model’s analyses to provide clinically relevant results

38. Dyad
Caregiver – Wife, 73 years, “good health”, no vision problems, no sleep-aid meds. Primary caregiver
Elder – Husband, 80 years, vascular dementia plus multiple co-morbidities, continent, needed assistance for all ADL’s and IADL’s, multiple meds included antidepressant but no sleep-aid
Elder received all primary care from the Cleveland VA Geriatrics Clinical team.
The couple had been married for approximately 50 years. Mr. X was diagnosed with probable vascular dementia three years previously and the couple had recently moved into an independent housing community for elders. Neither had significant visual problems and neither were taking medications for sleep or behavior disorders. Mr. X, who was continent, needed assistance for bathing, dressing, transfer, toileting and feeding and was dependent in all independent activities of daily living. His last Mini Mental Status Exam, 25/30, was completed more than three years before the study and he had resisted all repeat attempts at testing. Besides dementia syndrome, Mr. X had aortic stenosis, hyperaldosteronism, s/p CVA with right hemiparesis, diabetes mellitus, hypertension, gastritis, hyperlipidemia, and a history of depression. Mr X was on ASA, losartan, metformin, omeprazole, simvastatin, and citalopram, and no over the counter agents. Mrs. X, who was not a patient in the LSCVAMC geriatrics clinic, rated her health as good and reported that she was on medications for hypertension and hyperlipidemia but did not take any sleep-aid medication. She provided all care for her husband.
Recruited on a routine visit to clinic. Informed written consent obtained from wife for both parties. Assent obtained for elder.

39. Methods
Procedure - Light exposure and rest-activity data were collected over 7 consecutive days in November, 2007
Instruments
Assessment of sleep quality and habits
Home visit
Sleepwatch-L© (AMI, Ardsley, NY)
DaysimeterTM (Lighting Research Center, Rensselear Polytechnic Institute)
Mrs. X’s initial scores: Pittsburgh Sleep Quality Index was 6, indicating that she rated her previous month’s sleep as ‘poor.’
PSQ ITEMS: how often have you had trouble sleeping because you…can’t get to sleep within 30 mins, get up to use the BR, can’t breath comfortably? Taken meds to help you sleep, staying awake while driving, eating meals, social activities? Problem to get up enthusiasm to get things done?
Rating on Epworth Sleepiness scale: 3, indicating she got ‘enough sleep’. ITEMS: how likely are you to doze while sitting & reading, watch TV, lying down to rest in the afternoon, sitting inactive in a public place, in a car while stopped at a traffic light.
During the 7-day trial, she reported that she did not take any daytime naps, regularly went to bed about 10 pm and got up once during the night to use the bathroom. In the mornings she was up and out of bed for the day between 7-8 a.m. and did not nap during the day. In daily TC, she evaluated her previous night’s sleep quality as ‘fair or very good’ with only 1 of 7 nights rated as ’fairly poor.’
She reported that Mr. X was up for the day between 8-8:30 a.m., spent most of the day in his recliner, and that she considered him a “a good night-time sleeper” who did not disturb her own sleep even though she was aware of when he used the urinal.

40. DaysimeterTM Research prototype
Two light meters measure photopic and circadian light exposure
Actigraph measures movement

41. Results

42. Built Environment Independent living complex for seniors
Apartment: 640 square feet
Brown paneling and beige paint and carpet
One south facing window in bedroom
Sliding glass door onto porch (south facing)
Standard florescent lighting: kitchen and bath
Incandescent lighting: floor and table lamps

43. Ambient light exposure/24 hrs when out of bed (lux)
Range
Mean mins:
> 20 lux
> 500 lux
>1000 lux
Elder
0-449
191.5
0.0
Caregiver
0-3990
635.5
18.0
8.0
Dyad data
Light Norms (in lux)*
Sunlight
/reflective surfaces ,000
Overcast Day 1,000
Avg nursing home 50
Avg living room
Twilight 10
Full Moon 1
*From Turner, Br J Opthalmology

44. - Mean sleep efficiency % - Mean night sleep (mins)
ACTIGRAPHY
Caregiver wife
Demented husband
Sleep-rest
- Mean sleep efficiency %
- Mean night sleep (mins)
- Mean sleep latency (mins)
- Mean wake after sleep onset [WASO] (mins)
- Mean napping/24 hr (mins) 70
257 81
119 31
446 17
105 96
Intra-daily variability (0-2)
0.71
0.95
Inter-daily stability (0-1)
0.69
0.76
Caregiver 4.3 hours
Elder – 7.4 hours
Nighttime sleep: number of minutes scored as sleeping at night.
Sleep latency: number of minutes until sleep onset scored (first interval with > 20 minutes sleep).
>60 minsimpaired*
Sleep efficiency: percent of time scored as sleep beginning with first sleep interval. <70%impaired*
Napping: number of minutes scored as sleeping when not in bed.
WASO: number of minutes scored as awake after sleep onset to end of sleep; indication of sleep fragmentation. >90 minutesimpaired sleep*
Intra-daily variability (IV): indication of fragmentation of rest-activity/24 hours; theoretical range 0-2; a good r-a rhythm has low IV (Carvalho-Bos et al 2007)
Inter-daily stability (IS): indication of the strength of the coupling between the light-dark cycle and rest-activity cycle; theoretical range 0-1; good r-a rhythm\ has high IS (Carvalho-Bos et al 2007)
*”Cutpoints” used to provide “clinically meaningful” norms per Yaffee et al, p 238.

45. 24-hour Sleep and Light Caregiver Elder Caregiver 1112 wake minutes
328 sleep minutes
(7 episodes)
22.8% sleep

46. Caregiver
Per Daysimeter: caregiver phasor magnitude of [norms ] Indication of circadian entrainment/disruption

47. Entrained vs Disrupted
Human
Would like to talk about two specific environmental phase shifters: jet lag and shift work

48. Conclusions Daily light levels are very low
Little variation in light levels
Sleep
Neither caregiver or elder sleep well
Caregiver: poor circadian entrainment
Sleep disruption causes
Low lighting, little contrast
Frequent wake times at night

49. Support VISN 10 GRECC, Cleveland VAMC
Frances Payne Bolton School of Nursing, Case Western Reserve University, Cleveland, OH
Lighting Research Center, Rensselear Polytechnic Institute, Troy NY
General Electric Company, Nela Park, East Cleveland, OH 49

50. Team Tom Hornick, MD1,2 Patricia Higgins, PhD1,2
Mariana Figueiro, PhD3
Mark Rea, PhD3
Andy Bierman, MS3
John Bullough, PhD3
Bill Biers, PhD4
Mark Duffy, PhD4
Ed Yandek, BS4
1Case Western Reserve University
2Cleveland Veterans Affairs Medical Center
3Lighting Research Center, Rensselaer Polytechnic Institute
4General Electric Lighting, Nela Park

51. Next Steps
“Methodology issues in a tailored light treatment for persons with dementia" R01 – M. Figueiro, PI

52. Wikipedia, accessed 5/2010