As the weather grows colder and the days shorter, we are spending more time indoors and receiving a lot less natural light. Seasonal Affective Disorder, or depression caused by a lack of sunlight, has received a great deal of media attention but even without depression you too are affected by less sunlight.
Blue/green light found in full spectrum light like sunlight causes serotonin levels to rise making us feel alert and active. Red/Orange light, found in most of our indoor lighting, causes melatonin levels to rise making us feel more relaxed.
Perhaps you notice that you are more tired or sluggish these days - you may have even chalked it up to the busier schedule that follows summer vacation. The problem may not be your schedule but your lighting.
Consider the areas where you spend most of your waking hours during the day, especially where you work, and check your lightbulbs. If you find that you are using incandescent bulbs here simply replace them with full spectrum bulbs. Likewise consider the lighting next to your bed or places where you like to unwind before sleeping, if you have full spectrum or fluorescent lighting in these areas consider switching to incandescent bulbs here.
Make the switch and see how you feel, you may still miss summer but it may make the colder months more bearable.
Proper lighting is good design and good health!