Shining the Light on the MotionWatch8 Light Sensor for Sleep and Aging Research: What Can We Measure and What Are We Missing?

BACKGROUND: Poor sleep is common among older adults at risk for dementia and may be due to circadian dysregulation. Light is the most important external stimulus to the circadian clock and bright light therapy (BLT) has been used for >20 years to help realign circadian rhythms. However, the ability of field methods (e.g., actigraphy) to accurately determine the type and intensity of light is unknown. OBJECTIVE: We examined the ability of the MotionWatch8 (MW8) light sensor to determine: 1) light versus dark, 2) electrical light versus daylight, and 3) device-based BLT versus light which was not BLT. METHODS: We tested the MW8 under 17 daily light scenarios. Light exposure data was collected for 5 minutes during each scenario. Concurrently, we measured light exposure using the LT40 Light Meter, a sensitive measure of light intensity. We then developed individual cut-points using receiver operator characteristics analyses to determine optimal MW8 cut-points for 1) light versus dark; 2) electrical light versus daylight; and 3) light from a BLT box versus light which was not BLT. Bland-Altman plots tested the precision of the MW8 compared to the LT40. RESULTS: The MW8 accurately discriminated light versus dark (>32 lux), and electrical light versus daylight (<323 lux). However, the MW8 had poor accuracy for 1) discriminating BLT from light which was not BLT; and 2) low precision compared to the LT40. CONCLUSION: The MW8 appears to be able to discern light versus dark and electrical light versus daylight; however, there remains a need for accurate field methods capable of measuring light exposure.

Effect of a Multimodal Lifestyle Intervention on Sleep and Cognitive Function in Older Adults with Probable Mild Cognitive Impairment and Poor Sleep: A Randomized Clinical Trial.

BACKGROUND: Poor sleep is common among older adults with mild cognitive impairment (MCI) and may contribute to further cognitive decline. Whether multimodal lifestyle intervention that combines bright light therapy (BLT), physical activity (PA), and good sleep hygiene can improve sleep in older adults with MCI and poor sleep is unknown. OBJECTIVE: To assess the effect of a multimodal lifestyle intervention on sleep in older adults with probable MCI and poor sleep. METHODS: This was a 24-week proof-of-concept randomized trial of 96 community-dwelling older adults aged 65-85 years with probable MCI (<26/30 on the Montreal Cognitive Assessment) and poor sleep (>5 on the Pittsburgh Sleep Quality Index [PSQI]). Participants were allocated to either a multimodal lifestyle intervention (INT); or 2) education + attentional control (CON). INT participants received four once-weekly general sleep hygiene education classes, followed by 20-weeks of: 1) individually-timed BLT; and 2) individually-tailored PA promotion. Our primary outcome was sleep efficiency measured using the MotionWatch8© (MW8). Secondary outcomes were MW8-measured sleep duration, fragmentation index, wake-after-sleep-onset, latency, and PSQI-measured subjective sleep quality. RESULTS: There were no significant between-group differences in MW8 measured sleep efficiency at 24-weeks (estimated mean difference [INT -CON]: 1.18%; 95% CI [-0.99, 3.34]), or any other objective-estimate of sleep. However, INT participants reported significantly better subjective sleep quality at 24-weeks (estimated mean difference: -1.39; 95% CI [-2.72, -0.06]) compared to CON. CONCLUSION: Among individuals with probable MCI and poor sleep, a multimodal lifestyle intervention improves subjective sleep quality, but not objectively estimated sleep.

Buying time: a proof-of-concept randomized controlled trial to improve sleep quality and cognitive function among older adults with mild cognitive impairment.

BACKGROUND: Current evidence suggests that good quality sleep is associated with preserved cognitive function and reduced dementia risk in older adults. Sleep complaints are especially common among older adults with mild cognitive impairment (MCI), and this may contribute to their increased risk for progression to dementia. Thus, improving their sleep may be important for maintaining their cognitive health. Chronotherapy is a set of intervention strategies that can improve sleep quality through strengthening the entrainment of the biological clock to the solar light-dark cycle, and includes strategies such as (1) bright light therapy (BLT); (2) physical activity (PA); and (3) good sleep hygiene. Of these strategies, BLT is the most potent and is based on providing individualized timing to entrain circadian rhythms. Thus, a personalized chronotherapy intervention of individually timed BLT and individually tailored PA promotion, in conjunction with general sleep hygiene education may promote older adult sleep quality. We therefore aim to carry out a proof-of-concept randomized controlled trial (RCT) to examine the efficacy of such a personalized chronotherapy intervention to improve sleep quality among older adults with MCI. METHODS/DESIGN: This was a 24-week RCT of a personalized chronotherapy intervention aimed to primarily improve sleep quality as measured by the MotionWatch8©. Participants in the personalized chronotherapy group (INT) will receive four once-weekly, general sleep hygiene education classes, followed by 20 weeks of (1) individually timed BLT and (2) bi-weekly, individually tailored PA counseling phone calls in conjunction with receiving a consumer-available PA tracker-the Fitbit® Flex™. Ninety-six adults (aged 65-85 years) classified as having MCI (i.e., Mini-Mental State Exam (MMSE) ≥ 24; Montreal Cognitive Assessment (MoCA) ≤ 26; without dementia or significant functional impairment) will be randomized to either INT or a waitlist control group (CON). DISCUSSION: The results of this trial will help determine if a personalized chronotherapy intervention that includes individually timed BLT and individually tailored PA promotion, along with general sleep hygiene education can promote sleep quality among older adults at increased risk for dementia. Our results will help inform best practices for promoting sleep quality among older adults with MCI. TRIAL REGISTRATION: ClinicalTrials.gov , NCT02926157 . Registered on 6 October 2016.