Sunshine consists of waves of  electromagnetic energy produced by the sun. There are three main forms of solar radiation that are able to penetrate the earth's atmosphere:

• lower energy Infra-red radiation warms the atmosphere, land, and ocean producing a planet where plants grow and we can live comfortably. Green house gases such as carbon dioxide and methane act like a blanket trapping more infra-red radiation. Human activity has added more of these gases to the atmosphere causing the whole of the planet to warm by an average of at least 1.1deg. C since pre-industrial times. 
• Visible light waves - medium energy electromagnetic waves our eyes can detect. Visible light regulates our body clock and sleep cycle.
  • White morning light stimulates the production of cortisone in the brain. Cortisone increases alertness and energy levels. Spending some time outside or in a sunlit room in the morning energizes us and lifts our mood.
  • Orange-red evening light suppresses cortisone and increases melatonin. Melatonin reduces alertness and prepares the brain for sleep. In the evening use duller, warm-toned lights and avoid TV and other screens emitting white light.
• Ultraviolet (UV) light is higher energy radiation that can penetrate the surface layers of the skin. Most of the vitamin D in our body is produced in the skin using the energy from ultraviolet light.
  • The amount of sun exposure we need depends on the time of year, how far we are from the equator and how dark our skin is. For people with a lighter colour skin, wearing shorts and a short-sleeved top about 5 minutes of sunlight in the middle of the day in summer is enough.
  • Higher exposure to UV light can burn the skin and damage the DNA of the cells which increases the risk of skin cancer.