As we sleep, our body repairs and restores itself, good sleep is very important. At night, when we dream, the REM (Rapid Eye Movement) phase of sleep is vital for memory and learning, making sense of the day. The REM phase also replenishes helpful hormones including those which makes us feel good and give us a boost. Most adults over 18 need between 7-9 hours of sleep per night. Children and teenagers need even more. If you find you're sleeping less than 8 hours per night, then you're probably being deprived of the sleep you need to function at your best.