In the bible times, the Jews calibrated the day starting from sunrise (6 am) to sunset (6 pm) into twelve parts, each unit being an hour.
In those days, all field works stopped at 6.00pm, and labourers were then paid their wages (cons. Matt.20:1-10). So, the day was the period in which there was illumination from the sun that enabled men to see clearly (cons. Jn.9:4). It was in the light of this that the Lord Jesus spoke to His disciples who were fearful of returning to Judea – a place where danger apparently lurked (cons. Jn.11:7-8 cp. 10:30-31 ).
He expressed that security was guaranteed as He was walking in the light (cons. Jn.8:12, 14:6). At the back drop of that statement was the Awareness that when one walks (lives) in the light of God, he walks in the will of God; and when one walks in the will of God, safety is guaranteed (cons. Jn.7:1-6, 10-15, 8:58,59, 10:30-31, 19:9-11, Lk.13:31-33, Ps.91:1-16, 23:1-5).