Modern-day 24/7 lifestyle has taken over the 'night' and changed the biological order of millions of years of evolution. But scientists say the time piece that wakes us in the morning or the wristwatch that tells us we are late for dinner are not natural clocks. Embedded within our genes are the instructions for a biological clock that marks the passage of nearly 24 hours. This 'day within' regulates everything we do. Russell Foster, professor of circadian neuroscience at the University of Oxford, says, "Biological clocks or circadian clocks help time our sleep patterns, alertness, mood, physical strength, blood pressure, etc. This clock anticipates the differing demands of the 24-hour day. For instance, in anticipation of going to bed, our body temperature drops, blood pressure decreases, cognitive performance declines and tiredness increases. Before dawn, metabolism is geared up in anticipation of increased activity when we wake." Freedom over nature Neurosurgeon Dr Sunil Kutty says, "The fact is that it is not just the 24/7 lifestyle, but in some cases it is an occupational hazard, from which there is no escape." Research says those who go to bed early are alert in the mornings and those who do not like mornings want to keep going through the night. These differences are partly encoded within our genes, but they also change as we grow older. "In our early years of life, we tend to wake early, but by the time we become teenagers, our sleeping patterns change - our bed times and wake times go to later hours. But by the time we attain age of 55-60, we get up as early as we did when we were 10. This explains why today's young adults have a problem of getting up in the morning," says Foster. Psychiatrist Dr Kersi Chavda says, "Sleep deprivation is on a high amongst people today. They do not seem to sleep enough even the stipulated rest time that the body needs - seven to eight hours. This leads to heart ailments and depression." Psychiatrist Dr Kamaljit Singh says, "People usually rest sleeping. Everything needs rest, so does our brain. We perceive sleep as a state where the brain is resting, but the brain is actually very busy, doing the 'rest' of the work needed for various cognitive, hormonal and immunological functions." Due to lack of awareness of the importance of sleep, it is usually the first period to be shortened - if we need to buy some time from our busy awake schedule. An important exam coming up, sleep less; a party to enjoy, sleep less. For better health, we need to sleep well and have a fixed schedule of sleep and maintain the biological clock's rhythm.