Life expectancy can be increased simply by going outside. See, what happens when you go outside is that your skin gets exposed to sunlight. That exposure triggers cells in your skin to produce Vitamin D. This vitamin (really a prohormone, but let's not worry about that here) is essential for bone health and is turning out to be important in depression, heart disease, diabetes and just about everything.
Some estimate that 50% of adults have low levels of vitamin D, because we simply don't get outside that much (sitting by a window doesn't count, the glass filters too much of the sunlight). This is a shame, because maintaining vitamin D levels has to be the easiest and cheapest way to improve your health and increase your life expectancy. Getting outside for just 15 minutes a day and exposing your hands and face to sunlight is enough to maintain vitamin D levels in most cases.
If you are concerned about your vitamin D levels, your doctor can order a simple blood test that will tell you if your levels are low. If for some reason you can't get outside enough, there are vitamin D supplements that you can take (but getting outside is a better option, if you can).
Elderly people need to pay special attention to their vitamin D levels. If you are a caregiver, be sure to assist your loved one in getting outside just a little bit every day. Not only will with improve vitamin D levels, but it could also improve sleep because sunlight also regulates another hormone in the body called melatonin that controls your sleep cycle.
Read More on Vitamin D Deficiency.