Researchers have long maintained that we sleep to accomplish a neural or physiological function that cannot be completed when awake. Why else would higher animals waste a third of their lives sleeping when they could be doing more important things like looking after their families, working, or hunting? Some scientists believe sleeping helps recharge the body, while others think it is important for consolidating newly-formed memories. Now, there is new evidence which suggests that the purpose of sleep may be to forget some of the millions of new things we learn each day.