It is said that the average person needs seven-and-a-half hours sleep a night. However, averages conceal large differences and in truth, the amount of sleep each person requires varies considerably.
Age and personality play a fundamental part. Whilst most of us feel we need 7 to 8 hours sleep a night, there are some well-known examples of people who can get by with only 4 hours.
Generally, we need less sleep the older we get. Newborn babies seem to sleep for most of the day and a young child may require about 10 hours. Thereafter, some form of regression appears to take place, as teenagers seem to spend a great deal of time sleeping and experience great difficulty getting out of bed in the morning. However, this changes and as we pass into the 5th decade of our lives, we seem to require less and less sleep.
In addition to all this, our normal sleeping pattern changes through our adult years. For instance, an older person will sleep very deeply for the first 3 to 4 hours but wake more easily during the second half of the night.