EXPOSING YOURSELF TO EXTRA LIGHT DURING THE DAY INCREASES ALERTNESS!
If you feel sluggish and unable to focus in the middle of the day, try getting some sunlight to counteract these symptoms.
Years of research have shown that ambient light influences brain functions and different aspects of human physiology such as circadian rhythm, heart rate, and hormone release. While these functions have been recognized and studies have looked at the part of the brain that induces these responses at nighttime , little has been known about daytime responses to light. However, recent research in Belgium showed that the natural exposure to light that people can enjoy during the daytime not only made people more alert, but responses in certain parts of the brain got a "boost". http://www.livescience.com/humanbiology/060825_light_alert.html
With the majority of people spending their days indoors working, many feel the effect of a lack of exposure to natural light, which makes them feel tired, depressed and unfocused. By taking even just a few minutes to get outdoors and get some natural sun, these side effects can be easily counterbalanced. (Of course, it is important to protect any exposed areas of the skin from sun damage by wearing an appropriate sunscreen with a minimum SPF of 15.) Take a brief walk outdoors during work breaks to enjoy the natural light and recharge your batteries. Additional benefits of taking a few moments each day to walk in the fresh air- include increased exercise and the calming effect of communing with nature.
For those who live in climates that do not have natural sunlight for part of the year, look for alternative indoor light sources to create a similar affect. Many companies have created products that can be used as "light therapy" to counteract depression and other side effects experienced by individuals who reside in areas that lack natural light during seasonal periods. Many of these individuals suffer from Seasonal Affective Disorder http://www.ncpamd.com/seasonal.htm .
Look at these websites for Light Therapy products: