When Paul wrote this Epistle to the Ephesians, their great city was given over to idolatry, to the excitement of the Roman world with its theaters, its gladiatorial shows and religious celebrations. Spiritual darkness prevailed along with all kinds of vice. The days were evil. So Paul urges the Ephesian Christians to make time their own and bring forth the fruits of righteousness. To redeem time requires spiritual insight in order to sense that now is the moment to stand for Christ and for His truth.
Evil times tend to dull the mind.
All of us can look back on specific times that we thought were of little importance. Had we known it then, we would have done differently. We see now that it was a critical time for us. We had no intention of being spiritually asleep. We had no deliberate plan to neglect prayer and the study of God's Word, but we did.