Do you have trouble getting into sleep? Have you ever tried to find what is making you awake after midnight?

Grey may be the popular decor(装饰) color of the moment, but painting your bedroom grey actually stops you from falling asleep easily. Besides, reds, greens and purples can prevent a peaceful night’s sleep according to Natalie Armstrong, a sleep expert at mattress(床垫)company Sealy. She gives reasons.

★ Grey is usually used to represent(代表) sadness and loneliness, and it can send sad messages to our brain.

★ Too bright colors can put your brain into a state of high excitement, which can last long after you’ve turned off the light.

So what color is good for sleep? Blue. 如果你正打算粉刷卧室的墙，蓝色是最好的选择。Blue is easily received by certain cells(细胞)in your eyes. The cells then send a message directly to your brain, telling that you’re in a peaceful environment where you can fall asleep easily.

As we all know, smart phones can stand in the way of sweet dreams. Holding your smart phone or watching your favourite TV show in bed can put you in another “blue”environment. However, these blue lights are harmful, because they disturb(扰乱)our regular sleep-wake cycle and hurt our eyes.

Anyway, the color of bedroom walls is not the only and main reason to influence our sleep, but it really makes a difference. It is important to develop a good and healthy sleeping habit.

Different colours influence people differently. Red is an exciting colour. It creates an image（印象）of action, energy and danger. Red is often used in flags. 80%of the world's flags have red in them. A study in Germany showed that football teams wearing red are more successful.

Blue is a very calm colour. Businessmen usually wear dark blue suits. Blue is also a peaceful colour. The flag of the United Nations is light blue.

Yellow means freedom（自由）and green is a very relaxing colour. Some doctors nowadays wear green, because it's less tiring than white. White is a clean and strong colour. This is one reason why most doctors wear white coats. We believe in them more. People wearing grey do not want others to notice them. Brown is the opposite of black. It is warm and friendly.

There are many colours in the nature. But do you know if a colour has weight？I think you'll say "no". But I am afraid you are wrong. If you don't believe,you may do a small experiment（实验）.

First,put two objects with the same weight into two boxes. Then cover the box. Third,wrap（包裹）one box with a red piece of paper,the other with a white piece of paper. OK. Now hold the boxes with your hand one by one. It is certain that you will think the red one is a little heavier.

Why do you think so？A scientist found that different colours have different weights in a man's mind. So he did some tests and at last he got the result. That is to say,every colour has its own weight in our mind and their order is the same. The heaviest colour is red,then blue,green,orange,yellow and white.

The scientist told us that colours also have smell. Can you smell the colour？Of course not. Then why did the scientist say so？That is because every colour stands for a kind of light with a certain wavelength（波长）. It reaches our brain through sense organs（感觉器官）.

According to this discovery,scientists say that people accept the colours they like,and refuse the colours they hate. So your body and mind will be healthy by using the colours you like. Or you'll be nervous or even get ill. For example,if you stay in a room with red windows,wallpapers and furniture for two hours,you'll feel you have been there for four hours. But if the room is blue,you'll feel you have been there fur only an hour. Another example,if a person walks out of a red room and into a blue room,his temperature will fall. That means our body temperature will change with different colours.