Ayurveda says that our days are divided into time frames and these time frames relate to the three doshas (characteristics/constitutions that make up all living things including people) and therefore effect us in different ways. Have you ever noticed that you are really tired but then something happens around 10 o'clock and you get energy again and then don't feel like going to bed until midnight or well beyond? That second wind that kicks in is all due to the element of fire which is strongest from 10pm until 2am. As fire is transformative it's a great time for your body can repair itself and digest the food and thoughts of the day. By sleeping we give our bodies the best chance at doing this. By staying awake we are depriving our bodies of this natural gift and instead waste that energy watching TV, surfing the net or even working! This is not what nature intended.
The next stage in the cycle is between 2 and 6 am. This is the time where the elements of ether and air are strongest and a great time for creativity and dreaming. When we dream we allow our mind to process the events of the day and allow ourselves to delve into the unconscious mind. Even if we don't remember our dreams they are a highly valuable and important process that many psychologists, therapists and even artists have spent their lives honouring. Many people choose to get up at the end of this time period to meditate or do asana (yoga poses) as it's easier to tune into our higher state of consciousness and our mind has cleared itself and is ready for a new day.
As the sun starts to rise the the elements of earth and water begin to dominate and this explains why is can be difficult to get up and we feel sluggish. Have you ever woken up early and felt quite refreshed only to roll over and wake up a few hours later feeling heavy and dull? This is because the elements are at play, if we work with them we feel great but if we don't we will feel it.
So it is not as simple as getting 8 hours of sleep, it really does depend on when we get that sleep. Our body does not run according to a clock on the wall, it runs with the sun and the moon, and with nature and the elements that it is made from. if we honour this relationship we are honouring ourselves and allowing ourselves that best possible chance at wellbeing. I always thought I wasn't a morning person but now after allowing my body to convert back to it's natural rhythms and riding through a bit of a jet lag type type of adjustment I have discovered that I am a morning person. And yes I feel better for it. Give it a try and see how your mind and body react.