Read the text below and think of the word that best fits each gap. Use only ONE word in each gap. THE NEED FOR SLEEP How much sleep (1) ………………….. we really need? This can vary quite a lot between individuals. However, it is widely believed that between 6-8 hours (2) ………………….. healthy. What is particularly important is that this sleep happens (3) ………………….. the right time: that it fits in with our body’s natural rhythm. If you suffer from sleepiness or dysfunction during (4) ………………….. day then you are probably not getting enough sleep when you most need it. Typical symptoms of a lack of sleep (5) ………………….. low concentration, poor memory and feeling irritable. Getting the right amount of sleep is not only important in terms of being able (6) ………………….. function properly on a day to day basis but it also (7) ………………….. an impact on your overall health. Research suggests that people (8) ………………….. sleep between 6 to 7 hours per night are likely to live longer (9) ………………….. those who sleep less than 6 or more than 8 hours per night. One reason (10) ………………….. this is because of the effect sleep has on our immune system. There is a belief that old people need less sleep than other adults, however, this is not in fact true. The elderly need (11) ………………….. much sleep as when they were younger but changes to their body’s rhythm and health problems might make it more difficult for (12) ………………….. to sleep through the night. As a result (13) ………………….. is common for old people to fall asleep during the day.