Ayurvedic Clock Showing day & night cycle of nature & our life in accordance with that natural cycle. The figure shows the natural cycle of Vat, Pitta, Kapha dosha through day & night. 

Period of each dosha last 4 hours ,in that time doshas predominates the environment. If all human beings will have their daily routine following the changes in the nature their life will be according to the laws of nature because they will be gaining the support of nature for mind & body naturally.
  
e.g. 
1) Rising up around 6 am brings vitality & freshness of mind as this time is naturally influence by Vat dosha in the environment.

2) If the main meal of the day is taken at 12 –2 pm, it is in accord with natural law as Sun in the nature is having intense energy & heat which represents Pitta in the physiology helps to digest food well.

3) Going to bed around 10 pm is the proper time to begin the night sleep, after day activities the influence of kapha 6-10pm naturally favours relaxation, restfulness & sleep. If individual will regularly co operating with this natural influence of Kapha dosha by doing relaxing non exertional activities in the evening sleep will come most naturally & easily towards end of kapha period.