Morning blue light can help people recover from brain injuries and concussions, as it promotes falling asleep an hour earlier and waking up an hour earlier, which appears to be a better time for brain repair. Maintaining healthy circadian rhythms in the brain has also been linked to better sleep, improved neural function, and a reduced risk of Alzheimer's disease.
Scientists have been studying how the body's natural sleep cycle works for years by observing creatures such as fruit flies and humans to learn about the genetics of sleep.
The timing, duration, and quality of our sleep reflect our brain's ability to function optimally, and unhealthy circadian rhythms have been shown to impair glucose and cardiovascular regulation, promote obesity, diabetes, and hypertension, and increase the risk of neurodegenerative diseases. Moderate exposure to light at night, even from streetlights, can interfere with the sleep-wake cycle and overall health.
Circadian medicine involves the application of circadian rhythms to health care, which is often considered a part of sleep medicine. Evidence suggests that premature infants who receive 12 hours of light followed by 12 hours of darkness are discharged an average of two weeks earlier than those exposed to near-constant darkness or light.