The sleep pattern occurs in five stages. Stage I is light sleep in which one can be easily awakened and at times experience sudden muscle contractions preceded by a feeling of falling. During Stage II, eye movements stop and brain waves become slower. In Stage III sleep, very slow brain waves, called Delta waves, are combined with smaller and faster brain waves. Stage IV shows the development of primarily Delta waves and is referred to as deep sleep and is when children experience bedwetting or when nightmares occur. There is no eye movement or muscle activity during this stage. Stage V is REM, or rapid eye movement, sleep. During this stage of sleep, which occurs primarily in the second half of the night, heart rate and blood pressure increases,
