However as human beings we need to spend some time outdoors, it is our natural environment. Our bodies are designed to experience some sunlight and a green natural environment. We are of course still hunters and gathers who should be chasing our food in a green sunlit environment rather than gathering it an air-conditioned florescent tube lit supermarket.
Sunlight is our clock it is essential for keeping us in step with the earths rotate & it also signals the body to enter into an active state. When the body is awakened by the suns rays, serotonin, adrenalin, and cortisol levels go up, while melatonin levels go down.
The green outdoors natural green or blue environments also stimulates the brain to make melatonin – the hormone which makes you feel sleepy, and helps you to sleep well at night.
Training outdoors also stimulating our brains to make the right chemicals at the right time for example serotonin which helpswith muscle recovery , stress , moods and depression.
The short of it get out doors to feel happier and healthier.