Just as the seasons contain elements of the doshas, so do the hours of the day.  6 am to 10 am is Kapha time.  On awakening for the day, you probably feel slow, relaxed, and calm, all Kapha attributes.  10 am to 2 pm is Pitta time.  This is when we are at our most active and efficient.  Our digestion is strongest between noon and 1 pm, so we can take advantage of that by making lunch our largest meal of the day.  Pitta time is most productive for learning.  From 2 pm to 6 pm it is Vata time, when we are at our most creative.  The cycle repeats again in the evening hours.  Kapha time is 6 pm to 10 pm, when we slow down for rest.  Pitta time is 10 pm to 2 am when Pitta keeps our body warm, and we use this heat to digest food and rebuild body tissues.  And then Vata time is from 2 am to 6 am, when our creativity is expressed in the form of active dreams.