We spend about one-third of our life in sleep. Sleep is essential for the good health of both mind and body. Sleep is a state of unconscious rest. Even the conscious part of the mind is totally at rest, the subconscious part of the mind continues working and produces dreams. About five times during the night, we change from periods of deep sleep to periods of light sleep. And as morning approaches, the periods of light sleep become longer. We dream during the periods of light sleep. In dream, we make rapid eye movements and some body movements. If we wake up while we are dreaming, we can often remember the dream. No one really knows why we have dreams. But they appear to be an important part of sleep. Scientists have proved that almost everyone dreams three to five times during an 8-hour sleep. Those who claim that they do not dream, in fact, do not remember what they dreamt. Most dreams are based on events that happened during the day. Others involve fearful sights you might have seen when you were young. In other dreams, wishes you have had for a long time are also fulfilled. Some psychologists contend that during this activity, the brain ‘clears its registers’ to prepare for the next day’s conscious activities. During this period, the pattern of brain waves also changes. It is sometimes recorded for scientific observations. Its recording is called electroencephalogram. According to some people, their problems have been solved during dreams. Kekule, a great chemist, gave the structure of benzene molecule after having a dream. He was very puzzled about the structure, and one night in his dream, he saw a snake biting its tail while in whirling motion. That gave him the idea about molecular structure of benzene. Some people believe that dreams can foretell the future. So far, scientists have not been able to fully explain this phenomenon. Some dreams are pleasant, while others called ‘nightmares’, are frightening. In fact, all our dreams are related to our suppressed emotions, tears, desires and needs.