Color theory will state that yellow is one of the happiest colors because we associate it with the sun, flowers and baby chicks. Pink is also considered a happy color. Personal preference plays a role in which colors make us happy though too. Even though the color yellow is supposed to make us happy, it won't happen if you hate that color!
We also have to take into account that some people have color deficiency (their eyes don't see color accurately) and that blue is the most liked color of all.
There are good guidelines to learn on how to use color appropriately. Part of that equation should always involve how a person feels about the color or colors being used.
The colors that makes me feel better personally are bright colors and sometimes light purples.
Usually lighter colors make people feel good in environments like blue, yellow, green and pink. Many things influence beyond colors and I recommend that you look up about color theory because it is something very interesting to understand more deeply if you want to pursue a career as an interior design.
Good question, since color is so important in art and all kinds of design--fashion, interior, product, graphic and more. In terms of "light, dark" or neutral", it depends on the actual color. Of course what colors make you feel better could be a personal choice based on your own tastes and past experience, but there are many studies on the psychology of color, that indicate colors can affect our mood and behavior. It might have something to do with the wave lenghts of the different colors and how they affect our brains, but whatever, the effects of color is real to most people.
Some colors make us feel happy in terms of making us feel loved, or calm, or safe, or relaxed, while some colors make us feel not so good, in terms of feeling scared, or anxious, or angry or sad and so on. American English is filled with references to color and mood. Expressions include: "Feeling blue" means you are sad, "Seeing Red" means you are angry, "Looking at the world through rose-colored glasses" means you are a happy optimistic person.
If you have ever visited a nursing home, you'll probably see pink or light green or light yellow on the walls, which are supposed to have a calming effect on the residents. If you've ever visited a pre-school or day care center, you might notice brighter colors, such as deep blues, yellows, and reds. If you've ever watched a scary movie, you'll notice that dark blue, purple, gray, brown, or black colors often predominate. Think about what colors you wear in the Spring vs. the colors you wear in the Fall. Right now it is April, and the stores are filled with women's clothing in shades of pink, blue, yellow, and light purple, but by August, the color schemes will change to reds, oranges, deep greens, and browns.
Interesting to note that often businesses are very conscious about the colors they chose. One restaurant chain, Howard Johnsons, which no longer exists but was found on highways in the 1950's through the 1970's, was one of the first restaurant chains to use the psychology of color in their restaurants. They chose an orange and blue color scheme, and orange and blue are opposites on the color wheel, and thus creates a lot of visual energy. They chose these two colors because they did not want people to get to relaxed in their restaurants, they wanted their customers to eat and get back on the road, so the tables would be soon empty for the next round of customers.
Artists often think about their colors schemes in terms of "warm" colors, such as red, orange, or yellow, and "cool" colors like blue, purple and green. Warm colors give us a more energetic feeling, while cool colors have a more calming effect on us. Think of fire (reds, oranges, and yellows) vs. ice and snow (white, bluish/green). Pablo Picasso, a famous 20th century artist, did a whole series of paintings in shades of blue, often referred to as Picasso's "Blue Period". All the paintings have that period have a very quiet, calm, and thoughtful air to them. You can check them out online, and if you do, try to imagine them painted with bright colors, and ask yourself if you would have the same feelings about them. Mark Rothko is another 20th century artist who painted all sorts of color combinations in his large non-representational artworks, and they all have different feelings.
So, color is a very complex and important element in art and design. As you look around your world, try to be conscious of what colors you see on the buildings, interiors, fashions, and man made and natural things. How do these different colors make YOU feel?
Hope this helps!