Yes, research has shown that the people you surround yourself with affect your mood.

A study by Dr. Nicholas Christakis of Harvard Medical School and Dr. James Fowler of the University of California in San Diego found that an individual's social network can affect their happiness levels; the study looked at how individuals' moods changed when those around them were happy or unhappy.

The study found that people who associate themselves with cheerful people tend to be happier and have a better sense of well-being because one person's happiness can influence another's mood, which in turn affects the mood of yet another person, creating a positive chain reaction.

Emotionally close same-sex relationships and living in close proximity also amplifies the effect their attitude has on your disposition.

Research has found that the happiness of an individual extends up to three degrees of separation — so if a friend, relative, or neighbor within a mile becomes happy, the probability that you will be happy too increases by 25%.

With that being said, studies have shown that social support is essential for our mental health, so it's no secret that humans are social creatures, and social interaction is an essential part of our lives because it can influence our mood in both positive and negative ways.

One study found that people with strong social support experienced decreased stress, anxiety, and depression and boosted self-worth, comfort, and joy, which, in turn, can positively affect your mood. 

Which is why it's crucial to be selective about who you allow into your life, so choose to spend time with friends and family members who you have positive social interactions with because it increases oxytocin levels — a hormone that regulates our emotional responses and pro-social behaviors — which has a direct correlation with our mood.

5 Reasons Why It Matters Who You Spend Your Time With

Here are 5 reasons why it matters who you spend your time with:

1. You are influenced by those you surround yourself with. 

We've all heard the saying, "You are who you hang out with." which is accurate to a certain extent because although you are your own person and can think for yourself, the people you spend most of your time with do have an influence on you.

The people you spend the most time with have an enormous influence on your mood, how you view the world, and the expectations you have of yourself because you are more likely to adopt the beliefs and behaviors of those around you.

If you surround yourself with positive people, you will benefit from their empowering beliefs and optimistic view of the world; they can help you see the glass as half full instead of half empty.

On the other hand, if you surround yourself with negative people, you will more likely adopt their pessimistic and narrow-minded view of the world.

It’s important to choose carefully and be mindful of the types of people you spend your time with because their influence on you is much greater than you may realize.

2. Emotions are contagious.

Have you ever noticed how when you’re around someone who is happy, it’s hard not to feel the same way? Or when you’re around someone who is angry, it’s easy to get caught up in their emotions?

The reason being is emotions are contagious; this phenomenon is called "emotional contagion," and it occurs when we "catch" the emotions that other people are feeling and express them ourselves.

It's triggered by facial expressions, indirect human interactions, and by observing other people's behavior in direct and indirect interactions.

Emotional contagion is thought to be the result of mirror neuron activity when the neurons in our brain fire in response to seeing someone else performing an action; these neurons help you understand and feel the emotions that other people are experiencing.

Positivity is one of the most contagious emotions, which is why it's important to spend time with positive people that will make you feel happier and, hence, influence your mood; here are 10 best tips to surround yourself with positive people.

Negativity is just as contagious as positivity, if you're constantly around people who are complaining, gossiping, or being negative, it can start to wear on you; limit your exposure to people who complain all the time or are always negative because it can bring you down and affect your mood and health.

So if you want to improve your mood, surround yourself with positive people because their good vibes will rub off on you; do you want to be the one giving off good vibes? Here are 10 tips to help you do so. 

3. You control your life through your environment.

You have the power to control your life through your environment by choosing who you spend your time with.

If you want to live a happy and fulfilling life, it's important to be intentional about the company you keep and the things you do because these things can significantly impact your mood and overall well-being. 

If you're constantly around negative people and do things that make you unhappy, it will be harder for you to stay in a good mood.

But if you're around positive people and do things that make you happy, it will be easier for you to maintain a good mood and positive outlook on life.

4. You'll do, or you won't do more than you thought you could do. 

The people you spend the most time with will also affect your expectations of yourself and what you think you can achieve.

If you're around positive people, then it's going to be easy or you to believe in yourself and achieve your goals because they will encourage you to reach your full potential and make you believe that you can do anything you set your mind to by supporting you and helping you to see the possibilities instead of the limitations; if you have difficulty believing in yourself again, here are 9 best tips to help you gain confidence. 

But, if you're constantly around negative people, then it's going to be hard for you to believe in yourself and achieve your goals because they will limit your potential by bringing you down and making you believe that you can't do something because you're not good enough; here are 7 best tips to help you stand up to people who constantly put you down. 

So if you want to achieve great things and reach your full potential, surround yourself with positive people who will support you and help you reach your goals.

5. You'll either become a better or worse version of yourself.

It has been established that the people you spend the most time with influence you; with that being said, they will either make you a better or worse version of yourself.

If you're constantly around people who are always pushing you to be better, challenging you to grow, and encouraging you to reach your potential, then you'll become a better version of yourself.

On the other hand, if you're constantly around people who enable your bad habits, make excuses for you, and don't challenge you to be better, then you'll become a worse version of yourself.

Choose wisely who you spend your time with because they can either help you to grow into the best version of yourself or cause you to regress into your worst self.

So if you want to make positive changes in your life, it all starts with your mood, which is affected by the people you surround yourself with, so choose carefully!