One should get up early in the morning .There are so many benefits to getting up early in the morning. In Ayurveda it is stated that

Brahme muhurte uttishtetsvastho raksharthamayusha.
( ब्राम्हे मुहूर्ते उत्तिष्ठेत्स्वस्थो रक्षार्थमायुषः।

Early in the morning Means At what time?
Answer is...Just before the sunrise.

Benefits

1) when we get up early in the morning , at time of rising sun , vatadosh is in its prakrut avastha.
So defecation process becomes very easier.
There is no need of taking any stimulant for getting the urge of defecation.

2) Everyone can enjoy positive vibrations of morning time.
Mind becomes fresh , so the work efficiency increases.

3) you have ample of time to complete your work during the day so you can achieve your goals easily.
So one should get early in the morning to have good health and good life.