Days get shorter and the weather gets colder, there is less sunshine to go around. This means less vitamin D for our skin to absorb. Vitamin D is hard to find in foods. It is fortified in milk and orange juice, but many Americans do not drink either of them. All these factors cause an increase in the number of people that suffer from vitamin D deficiency during the winter months.
Symptoms of vitamin D deficiency include skeletal pain and muscle weakness. Vitamin D deficiency can be hard to detect because these symptoms make you feel tired and drained of energy. There are so many things that can cause energy drainage (lack of sleep, poor nutrition, lack of hormone regulation, and over eating just to name a few). And let’s be honest, we all want to be a couch potato every now 
and then. So how are you supposed to know if vitamin D is the cause of your weakness?
You can always get tested for vitamin D deficiency, but you can also up your intake of it and see if that improves you energy levels. Supplementation can help you get your vitamin D levels back up to normal when UV rays from the sun are not available. Supplementation is highly recommended for everyone during colder months, especially if you live in an area that stays cloudy during the winter time. You can also try to incorporate eggs (including the yolk), liver, and fish to up your dietary intake of vitamin D, now that the days get shorter.