Perchance To Dream.
Modern life, with its preponderance of inadequate exposure to natural light during the day and overexposure to artificial light at night, is not conducive to the body’s natural sleep/wake cycle.
It’s an emerging topic in health, one that UConn Health (University of Connecticut, Farmington, Conn.) cancer epidemiologist Richard Stevens has been studying for three decades.
“It’s become clear that typical lighting is affecting our physiology,” Stevens says. “But lighting can be improved. We’re learning that better lighting can reduce these physiological effects. By that we mean dimmer and longer wavelengths in the evening, and avoiding the bright blue of e-readers, tablets and smart phones.”
Those devices emit enough blue light when used in the evening to suppress the sleep-inducing hormone melatonin and disrupt the body’s circadian rhythm, the biological mechanism that enables restful sleep.
Stevens and co-author Yong Zhu from Yale University explain the known short-term and suspected long-term impacts of circadian disruption in an invited article published in the British journal Philosophical Transactions of the Royal Society B.
“It’s a new analysis and synthesis of what we know up to now on the effect of lighting on our health,” Stevens says. “We don’t know for certain, but there’s growing evidence that the long-term implications of this have ties to breast cancer, obesity, diabetes, and depression, and possibly other cancers.”
As smartphones and tablets become more commonplace, Stevens recommends a general awareness of how the type of light emitted from these devices affects our biology. He says a recent study comparing people who used e-readers to those who read old-fashioned books in the evening showed a clear difference, the e-readers showed delayed melatonin onset.
“It’s about how much light you’re getting in the evening,” Stevens says. “It doesn’t mean you have to turn all the lights off at 8 every night, it just means if you have a choice between an e-reader and a book, the book is less disruptive to your body clock. At night, the better, more circadian-friendly light is dimmer and, believe it or not, redder, like an incandescent bulb.”
Using melatonin could provide more and better quality sleep compared to using an eye mask and earplugs in a simulated noisy and illuminated environment, according to research published in open access journal Critical Care. This study was carried out on healthy subjects but could have future implications for intensive care unit (ICU) patients.
Melatonin is the hormone secreted by the body to regulate sleep, usually in periods of darkness. Synthetically produced melatonin is used to boost the body’s own melatonin levels to treat some sleep disorders, and sometimes as a means of overcoming jet lag. In ICUs, disturbances throughout the night, caused by noise and light, have been linked to slower recovery. This has led clinicians to investigate ways of reducing sleep disturbances.
Researchers from Capital Medical University in Beijing recruited 40 healthy participants to study the effects simulated ICU conditions had on sleep patterns. The research was conducted in the sleep lab of Fuzhou Children’s Hospital of Fujian Province in collaboration with Professor Ling Shen. For the first four nights all participants underwent a baseline/adjustment period. During this time they slept in a sleep laboratory where on alternating nights a recording from a typical night shift at an ICU was played and light levels were the same as in the hospital.
After the first four nights the participants were randomly divided into four equal groups but continued to sleep in the simulated ICU. The first group did not receive any sleep aid. The second were provided with eye masks and earplugs. The third group took 1mg of fast-release oral melatonin when going to bed. The final group of participants was given a placebo. The participants did not know if they were receiving melatonin or placebo.
During the study period all participants’ melatonin levels were tested hourly by taking blood samples. The quality of sleep was assessed using specialist equipment that measured brain activity, eye movement and muscle tension. Anxiety levels and sleep quality were also evaluated by getting participants to self-evaluate the following morning.
It was found that all sleep patterns were disturbed by exposure to the simulated ICU environment. This resulted in feelings of anxiety and reduced quality of sleep. Those participants that used either eye masks and earplugs or oral melatonin had improved sleep. Those who took melatonin were found to have decreased awakenings during the night even compared to the eye mask and earplugs group. The quality of the sleep was also found to be much improved for those taking melatonin, with reported lower anxiety levels and increased REM sleep, thought to be linked to improved cognitive restoration.
As this study was carried out on a small number of healthy subjects over a nine-hour period it may not give a full representation of the various sleep disturbances that can occur in an ICU over 24 hours. They say future studies will need to be carried out on a larger group of diverse participants. Consideration would also need to be given for the administration of oral melatonin to critically ill patients who may also be taking other medications.
Lead researcher, Professor Xiu-Ming Xi from Fuxing Hospital, Capital Medical University, says: “Both use of oral melatonin and use of earplugs and eye masks improve sleep quality at different levels, especially melatonin. Discomfort from use of earplugs and eye masks might affect sleep quality, which wasn’t reported with melatonin. Therefore, compared to earplugs and eye masks, melatonin showed up the better performance in effectiveness and the tolerance of participants.”
Ben-Gurion University of the Negev (BGU) researchers have developed a groundbreaking approach to determine sleep quality using their new breath sound analysis (BSA). This is less expensive and invasive than current polysomnography (PSG) technology, according to a new study published on PLOS Online.
“One of the main goals of sleep medicine today is to improve early diagnosis and treatment of the ‘flood” of subjects presenting with sleep disorders,” says Prof. Yaniv Zigel Ph.D., head of the Biomedical Signal Processing Research Lab in BGU’s Department of Biomedical Engineering.
“We’ve developed a non-contact ‘breathing sound analysis’ algorithm that provides a reliable estimation of whole-night sleep evaluation for detection of sleep quality, snoring severity and Obstructive Sleep Apnea (OSA). It has the potential to reduce the cost and management of sleep disorders compared to PSG, the current standard of treatment, and could be used at home.”
PSG requires a full night sleep center stay and subjects are connected to numerous electrodes and sensors that are attached to the patient to acquire signals and data from electroencephalography (EEG), electrooculography (EOG), electromyography (EMG), and electrocardiography (ECG) tests. The data is processed and visually examined or mathematically transformed manually in order to reveal insights about sleep/wake states and many aspects of physiology. “This procedure is time-consuming, tedious and costly due to complexity and the need for technical expertise; the market is begging for a better solution,” says Eliran Dafna who conducted this study as part of his Ph.D. research.
In the study, the researchers measured whole-night breathing sounds from 150 patients using both ambient microphones and PSG simultaneously at a sleep laboratory. The system was trained on 80 subjects and a validation study was blindly performed on the additional 70 subjects. A set of acoustic features quantifying breathing patterns was developed to distinguish between sleep and wake segments. Sleep quality parameters were calculated based on the sleep/wake classifications and compared with PSG for validity.
When comparing sleep quality parameters, there were only minor average differences in the measurements between PSG and BSA. Measuring 150,000 individual time segments (epochs), the BSA epoch-by-epoch accuracy rate for the validation study was 83.3 percent with 92.2 percent sensitivity measuring sleep as sleep.
“The results showed that sleep/wake activity and sleep quality parameters can be reliably estimated solely using breathing sound analysis,” says Prof. Ariel Tarasiuk of BGU’s Department of Physiology and head of the Sleep-Wake Disorders Unit, at Soroka University Medical Center. “This study highlights the potential of this innovative approach to measure sleep in research and clinical circumstances. Clearly, the transition of this technology to at-home sleep evaluation depends on third party reimbursements for the use of home study equipment.”