Tired all the time? It could be the change of seasons.

In the animal world, light has a profound effect on everything—from feeding and hunting to migration and reproduction. As humans, we are no exception. When the amount of daylight changes from season to season, our biological rhythms can get 'out of whack,' resulting in disrupted sleep patterns.

Most people are familiar with the term "insomnia," which means the inability to fall asleep. A term that we are less familiar with is "hypersomnia" or "excessive daytime sleepiness." People suffering from hypersomnia have trouble staying awake during the day. They may also complain of a general lack of energy, trouble concentrating, and sometimes even memory problems.

There are many potential causes of hypersomnia, including sleep disorders like narcolepsy, sleep apnea, or restless leg syndrome. However, one common cause that's often overlooked is disorders of the alignment of the internal body clock to external factors or "circadian rhythm sleep disorders."

Each year on September 22, the earth experiences an autumnal equinox. This means there is no tilt to the earth's axis on this day…it stands straight up and down, resulting in an equal amount of lightness and darkness for everyone. After this day, people living in the northern hemisphere begin to receive less light each day as the earth tilts away from the sun.

As the days become shorter and the nights longer, our biological clock (circadian rhythm) could get disrupted. For most this change is hardly noticeable as the body learns to adjust and reset its internal clock. However, for those who suffer from Seasonal Affective Disorder (S.A.D.), this can lead to changes in serotonin and melatonin levels, which affect sleep patterns and mood. The result is seasonal depression, which when left untreated, can lead to social withdrawal, problems at school or work, substance abuse, and even suicide.

The best way to prevent "the winter blues," is to take action early. Here are a few simple ways to help your body adjust to the changing seasons, reset its biological clock and feel better overall:

• Exercise. In addition to all the physical benefits of exercise, a daily workout prompts the body to release "feel good hormones" that help to improve mood and boost energy levels. As long as it is not too close to bedtime, it may help you sleep better at night.
• Eat healthy. Just because summer is over does not mean we should discontinue our healthy eating habits and rely on those high-fat comfort foods. Avoid refined and processed foods like white breads, white rice, and sugar, which are low in nutrients. Instead, choose a diet with whole grains, lots of fruits and veggies, and at least eight cups of water per day.
• Take your Vitamin D. Sunshine provides much of the Vitamin D our bodies require throughout the summer months. However, during the winter, when we are cooped up inside, most of us do not receive enough Vitamin D. In addition to your daily multi-vitamin, consider a Vitamin D supplement. Check with your doctor on a dosage level that best fits your needs.
• Avoid binge drinking. Moderate drinking is fine for most people, but having more than three drinks in one sitting is unhealthy and dangerous. While many people tend to reach for a drink to give them a mood booster when they are feeling down, the opposite is actually the case. Alcohol is a depressant, which could naturally worsen your mood rather than improve it. If you are not habituated to the use of alcohol, it may help you fall asleep more quickly; but sleep is often disrupted in the second half of the night. It also gives rise to the possibility of increased nightmares and sleep apnea. Sleep problems could persist for years, even after one has been sober for a while.
• Cut the caffeine. You may think those cups of joe or diet sodas are a good "pick me up," but the truth is, all that caffeine could be wreaking havoc on your ability to get a good night's sleep. Try switching to decaffeinated coffee or herbal tea if possible. Avoid more than 250 mg of caffeine per day and try to cut out all caffeine intake after noon if you are having problems with sleep at night.
• Stay on schedule. Try keeping a regular sleep schedule with six to eight hours of sleep per night. If you are having trouble falling asleep, try sleeping with a fan to create some background noise. If you are still unable sleep after 20-30 minutes, get up, make a warm glass of milk or a cup of herbal tea, and try reading something uninteresting for a while. Avoid bright lights, TV, and using your computer in bed. If all else fails, you could try the intermittent use of an over-the-counter sleep aid after checking with your health care provider.