Some useful advice from Chāṇakya in his Arthashastra (Book 1, Chapter 19):
| First 1½ hrs. after sunset | Interview with secret agents |
| Second 1½ hrs. after sunset | Personal: bath, meals, study |
| Third & Fourth 1½ hrs. after sunset and First 1½ hrs. after midnight | Retire to the bed chamber to the sound of music, sleep |
| Second 1½ hrs. after midnight | After waking to the sound of music, meditate on political matters and on work to be done |
Developed in the period around 300BC when the Maurya Empire was active, and Chāṇakya was advisor to its first emperor, Chandragupta.
arbitrary constant 