Does sleeping late in night iimproves our efficiency?

I don't think it matters whether you sleep in late so much as it matters if you get enough sleep. Different people need different amounts and even that varies according to what you're doing, stress, weather and a lot of other things. I think that if we listen to our bodies and minds, we know whether we're getting enough sleep or not. Always having to use an alarm clock to wake up is a good sign that we're not sleeping enough. I do believe that not enough sleep will ruin your health. Sleep is the time when our bodies repair themselves of the normal wear of every day activity. If they don't have time to do that, it will cause problems.

The best way to get your sleep is reguarily get the same amount of sleep and go to sleep at the same time every day. You should also find your optimal sleeping time, as sleep cycles are around 1.5 hours, it varies from people to people so you should try sleeping around 7.5 or 9 hours a day, and seeing how that works it.