Let me tell you about my bedroom. There are many kinds of furniture in my bedroom. In the centre of my room, there is my bed. The bed is made of wood. There is a nice bed cover and a warm blanklet for my bed. On the right side of my bed, there is a wardrobe. I put my clothes in it. On the left side of my bed, there is a bookshelf. I put my books in there. There is a table and a chair next to the shelf. I usually sit there to study. On the table, there is a desk lamp. When I study in the evening, I always turn on the lamp. When I study in the evening, I always turn on the lamp. There is also an alarm clock on my table. I set the alarm in the evening before I go to bed. It wakes me up in the morning. I always clean my bedroom every day. I arrange things neatly to make my bedroom comforable to live in.

What is the function of the alarm clock?