***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The photopigment in the human eye that transduces light for circadian and neuroendocrine regulation , is unknown . The aim of this study was to establish an action spectrum for light-induced melatonin suppression that could help eluci date the ocular photoreceptor system for regulating the human pineal gl and . Subjects ( 37 females , 35 males , mean age of 24.5 ± 0.3 years ) were healthy and had normal color vision .  Full-field , monochromatic light exposures took place between 2:00 and 3:30 A.M. while subjects ' pupils were dilated . Blood sample s collected before and after light exposures were quantified for melatonin . Each subject was tested with at least seven different irradiances of one wavelength with a minimum of 1 week between each nighttime exposure . Nighttime melatonin suppression tests ( n = 627 ) were completed with wavelengths from 420 to 600 nm . The data were fit to eight univariant , sigmoidal fluence – response curves ( R2 = 0.81–0.95 ) . The action spectrum constructed from these data fit an opsin template ( R2 = 0.91 ) , which identifies 446–477 nm as the most potent wavelength region providing circadian input for regulating melatonin secretion . The results suggest that , in humans , a single photopigment may be primarily responsible for melatonin suppression , and its peak absorbance appears to be distinct from that of rod and cone cell photopigments for vision . The data also suggest that this new photopigment is retinaldehyde based . These findings suggest that there is a novel opsin photopigment in the human eye that mediates circadian photoreception STUDY OBJECTIVES Sleep pattern and circadian rhythms are regulated via the retinohypothalamic tract in response to stimulation of a subset of retinal ganglion cells , predominantly by blue light ( 450 - 490 nm ) . With age , the transmission of blue light to the retina is reduced because of the aging process of the human lens , and this may impair the photoentrainment of circadian rhythm leading to sleep disorders . The aim of the study was to examine the association between lens aging and sleep disorders . DESIGN Cross-sectional population based study . SETTING The study was performed at the Research Center for Prevention and Health , Glostrup Hospital , Denmark and at the Department of Ophthalmology , Herlev Hospital , Denmark . PARTICIPANTS An age- and sex-stratified sample of 970 persons aged 30 to 60 years of age drawn from a sample r and omly selected from the background population . INTERVENTIONS Not applicable . MEASUREMENTS AND RESULTS Sleep disturbances were evaluated by a combination of question naire and the use of prescription sleeping medication . Lens aging ( transmission and yellowing ) was measured objective ly by lens autofluorometry . The risk of sleep disturbances was significantly increased when the transmission of blue light to the retina was low , even after correction for the effect of age and other confounding factors such as smoking habits , diabetes mellitus , gender , and the risk of ischemic heart disease ( P < 0.0001 ) . CONCLUSIONS Filtration of blue light by the aging lens was significantly associated with an increased risk of sleep disturbances . We propose that this is a result of disturbance of photoentrainment of circadian rhythms ABSTRACT This secondary analysis examined whether the benefits of bright light therapy on depression are greater in persons with mild/moderate or severe dementia . Exploratory analyses were also conducted to determine if bright light treatment targets different depressive symptom clusters based on dementia severity . Analyses using total scores from the instruments , Depressive Symptom Assessment for Older Adults and the Cornell Scale for Depression in Dementia , showed that bright light exposure is an equally effective intervention for depression in persons with both mild/moderate and severe dementia . Analyses of individual depressive subscales revealed that for disagreeable behavior and sleep impairment , bright light therapy appears to have greater benefits in persons with severe dementia than for those with mild/moderate dementia . Overall , this investigation supports the use of bright light therapy to treat depression regardless of dementia severity This study examined the effects of bright light exposure on three measures of depression and four measures of agitation in persons with dementia residing in long-term care . Using a r and omized controlled design , participants were r and omly assigned to receive either bright light ( n = 30 ) or low intensity light ( n = 30 ) for eight weeks . Bright light exposure was associated with significant improvement in depression and agitation , while participants receiving low intensity light displayed higher levels of depression and agitation or no significant change . Findings support the use of bright light exposure to reduce depression and agitation in this population Ten elderly subjects with severe dementia were given bright light ( 5000 - 8000 lux ) for 45 min each morning for 4 weeks . Two rating scales of behavioral symptoms in dementia were used as outcome measures : Cohen-Mansfield Agitation Inventory ( CMAI ) and Behavior Pathology In Alzheimer 's Disease Rating Scale ( BEHAVE-AD ) , a scale for sleep-wake disturbances , and actigraphy to monitor activity rhythm . Behavioral symptoms improved with treatment . No changes in sleep-wake measures were found . There was an advance of the activity rhythm acrophase during treatment . These results suggest that short-time bright light improves behavioral symptoms and aspects of activity rhythm disturbances even in severely demented subjects Two hundred ten community-dwelling patients with Alzheimer 's disease were examined prospect ively by psychiatrists as part of a longitudinal study . Twenty-five of these patients who were institutionalized during the next 3 years were then matched to 25 patients who were not institutionalized  , and the groups were compared . The patients who had been institutionalized had higher scores on st and ardized psychiatric rating scales but not on formal neuropsychological tests of cognition . These results suggest that potentially treatable ( noncognitive ) behavioral and psychiatric symptoms are risk factors for institutionalization , and that treating these symptoms might delay or prevent institutionalization of some patients We investigated whether low intensity dawn-dusk simulation ( DDS ) , a ' naturalistic ' form of light therapy design ed to embed sleep in its accustomed phase , could improve the disturbed circadian rest-activity cycle , nocturnal sleep and and /or cognitive functions in dementia . A protocol of 3 weeks each of baseline , treatment and follow-up was completed by 13 patients ( 85yr old+/-5yr , MMSE 14+/-5 ; n=9 DDS versus n=4 ' placebo ' dim red light ) who wore an activity/lux monitor throughout . There were no significant changes in clinical or cognitive status , nor modification of circadian stability or amplitude characteristics of the rest-activity cycle . However , two aspects of sleep responded to DDS but not to dim red light . The main sleep episode was 1:14h earlier during treatment ( p=0.03 ) compared with before and after DDS . With respect to actimetry-determined sleep variables , the DDS group tended to have shortened ' sleep latency ' , longer ' sleep duration ' , more nocturnal immobility and less nocturnal activity than the dim red group ( p<0.1 ) . In parallel , nighttime light exposure tended to be reduced ( p=0.07 ) . These promising findings -after only 3 weeks of light treatment in elderly patients with advanced dementia-suggest that the circadian timing system remains functionally responsive even to low intensity DDS light . Increasing zeitgeber strength is an important strategy for improving sleep quality and timing in dementia , and DDS light therapy may provide one of the appropriate means to do so Background The ' Hawthorne Effect ' may be an important factor affecting the generalisability of clinical research to routine practice , but has been little studied . Hawthorne Effects have been reported in previous clinical trials in dementia but to our knowledge , no attempt has been made to quantify them . Our aim was to compare minimal follow-up to intensive follow-up in participants in a placebo controlled trial of Ginkgo biloba for treating mild-moderate dementia . Methods Participants in a dementia trial were r and omised to intensive follow-up ( with comprehensive assessment visits at baseline and two , four and six months post r and omisation ) or minimal follow-up ( with an abbreviated assessment at baseline and a full assessment at six months ) . Our primary outcomes were cognitive functioning ( ADAS-Cog ) and participant and carer-rated quality of life ( QOL-AD ) . Results We recruited 176 participants , mainly through general practice s. The main analysis was based on Intention to treat ( ITT ) , with available data . In the ANCOVA model with baseline score as a co-variate , follow-up group had a significant effect on outcome at six months on the ADAS-Cog score ( n = 140 ; mean difference = -2.018 ; 95%CI -3.914 , -0.121 ; p = 0.037 favouring the intensive follow-up group ) , and on participant-rated quality of life score ( n = 142 ; mean difference = -1.382 ; 95%CI -2.642 , -0.122 ; p = 0.032 favouring minimal follow-up group ) . There was no significant difference on carer quality of life . Conclusion We found that more intensive follow-up of individuals in a placebo-controlled clinical trial of Ginkgo biloba for treating mild-moderate dementia result ed in a better outcome than minimal follow-up , as measured by their cognitive functioning . Trial registration Current controlled trials : IS RCT OBJECTIVE Preliminary data suggest that morning bright light might improve symptoms of agitation , a serious problem in patients with dementia . The authors exp and on an earlier pilot study by evaluating the effect of bright light therapy on agitated behavior in a large sample of patients with severe dementia . METHODS Ninety-two patients were r and omly assigned to morning bright light , morning dim red light , or evening bright light .  Agitation was rated by research staff who observed the patients every 15 minutes throughout the treatment period and by caregivers at one time-point before and one time-point after treatment . RESULTS Morning bright light delayed the acrophase of the agitation rhythm by over 1.5 hours . Bright light was associated with improved caregivers ' ratings but had little effect on observational ratings of agitation . CONCLUSION Although the result that light shifted the peak of the agitated behavior might be generalizable to patients with milder forms of AD , the fact that agitation was not ameliorated might not be . Because the suprachiasmatic nucleus ( SCN ) of patients with severe AD is likely to be more degenerated , and the circadian activity rhythms deteriorate as the disease progresses , it is still possible that patients with more intact SCNs , that is , patients with mild or moderate AD , might benefit from light treatment even more than those with severe AD OBJECTIVES To compare the effects of physical resistance strength training and walking ( E ) , individualized social activity ( SA ) , and E and SA ( ESA ) with a usual care control group on total nocturnal sleep time in nursing home and assisted living residents . DESIGN Pretest-posttest experimental design with assignment to one of four groups for 7 weeks : E ( n=55 ) , SA ( n=50 ) , ESA ( n=41 ) , and usual care control ( n=47 ) . SETTING Ten nursing homes and three assisted living facilities . PARTICIPANTS One hundred ninety-three residents were r and omly assigned ; 165 completed the study . INTERVENTION The E group participated in high-intensity physical resistance strength training 3 days a week and on 2 days walked for up to 45 minutes , the SA group received social activity 1 hour daily 5 days a week , the ESA group received both E and SA , and the control group participated in usual activities provided in the homes . MEASUREMENT Total nocturnal sleep time was measured using 2 nights of polysomnography before and 2 nights of polysomnography after the intervention . Sleep efficiency ( SE ) , non-rapid eye movement ( NREM ) sleep , rapid eye movement sleep , and sleep onset latency were also analyzed . RESULTS Total nocturnal sleep time was significantly greater in the ESA group than in the control group ( adjusted means 364.2 minutes vs 328.9 minutes ) , as was SE and NREM sleep . CONCLUSION High-intensity physical resistance strength training and walking combined with social activity significantly improved sleep  in nursing home and assisted living residents . The interventions by themselves did not have significant effects on sleep in this population OBJECTIVES To test the effects of walking , light exposure , and a combination intervention ( walking , light , and sleep education ) on the sleep of persons with Alzheimer 's disease ( AD ) . DESIGN R and omized , controlled trial with blinded assessors . SETTING Independent community living . PARTICIPANTS One hundred thirty-two people with AD and their in-home caregivers . INTERVENTIONS Participants were r and omly assigned to one of three active treatments ( walking , light , combination treatment ) or contact control and received three or six in-home visits . MEASUREMENTS Primary outcomes were participant total wake time based on wrist actigraphy and caregiver ratings of participant sleep quality on the Sleep Disorders Inventory ( SDI ) . Secondary sleep outcomes included additional actigraphic measurements of sleep percentage , number of awakenings , and total sleep time . RESULTS Participants in walking ( P=.05 ) , light ( P=.04 ) , and combination treatment ( P=.01 ) had significantly greater improvements in total wake time at posttest ( effect size 0.51 - 0.63 ) than controls but no significant improvement on the SDI . Moderate effect size improvements in actigraphic sleep percentage were also observed in active treatment participants . There were no significant differences between the active treatment groups and no group differences for any sleep outcomes at 6 months . Part 
    Output:
    
The use of crossover design s and too high illumination as placebo lights might have nullified positive effects of BLT .