Sleep is a regularly recurring condition of rest for the body and mind, during which the eyes are usually closed, and there is little or no consciousness. Research shows that sleeping patterns deviate for different cultures, and change in these patterns can be found significantly for cultures that use a lot of artificial light and the ones which do not.
Investigation shows that the cultures, which do not believe in using much artificial light, like old times, experience broken-up sleep patterns. These people normally sleep in fits and bouts for a few hours at a time, waking at intervals for a variety of reasons. The invention of light into the households has actually shown a change in sleeping habits, resulting in more solid sleep as compared to the earlier naps.
Studies are still being conducted into how bright lights help change the sleep-wake schedule of a person and how do they deal with depression. Researchers have hypothesized that light entering the visual cortex causes a reaction which triggers the suppression of melatonin. This hormone is a major catalyst in our sleep-wake cycle. It can induce sleep even when our bodies are not sufficiently tired and thus, can also be expected to work in the opposite way, given different stimuli, having a major effect on the way we sleep.
Initial theories suggested a pathway from the retina to this specific area of the brain. On the other hand, some latest research indicated that bright light applied to the back of the knee of an individual could shift human circadian rhythms (Daily sleep-wake cycle). This suggests that the bloodstream, in addition to the neurons of the visual pathways, might affect the biological clock.
Light may also help the mood of a person when he/she wakes up, specifically when suffering from certain disorders. Seasonal Affective Disorder (SAD), is a good example of such an adversity. More commonly identified as the winter blues, it is a mood disorder which some people, who may have absolutely normal mental health in all other circumstances and throughout most of the year, face in cold weather. Sometimes, this phenomenon is also observed in other seasons, but is quite rare. Normally, this condition occurs repeatedly on an annual basis.
The symptoms of this disorder include abnormal sleep patterns. Light therapy, involving light bulbs providing intense illumination, is used as a form of treatment, which is effective.
When somebody is sleeping and the curtains in his/her room are pulled apart to allow in the sunlight, the person normally awakens. The light affects the sleep of that individual, causing the eye lids to open. However, any person woken up in this manner is bound to be irritated.
Lately, many products in the market include lamps with light that increases the intensity gradually, so that a person wakes up slowly and is not exposed to severely intense light all of a sudden. Most people would find the latter option more pleasant, and would prefer it to intense light. Therefore, it is obvious that light plays a role in the wake up patterns of the up.
