It’s been proven. Clutter is a bummer — literally.

Dishes in the sink, toys throughout the house, stuff covering every flat surface. This clutter not only makes our homes look bad, but makes us feel bad, too.

Several studies over the past 10 years have connected clutter with behavioral and mental health issues. Research from health care heavy hitters — think Mayo Clinic, Princeton University, and UCLA — have found that clutter can increase the stress hormone cortisol and cause lower productivity, insomnia, weight gain, procrastination, and depression. Now that’s a list of health problems you don’t want to take to your next checkup.

UCLA’s Center on Everyday Lives and Families (CELF) explored in real time the relationship between 32 California families and the objects in their homes. The resulting book, “Life at Home in the Twenty-First Century,” is a landmark look at how middle-class Americans use the space in their homes and interact with the things they accumulate over a lifetime.

Our overworked closets are overflowing with things we rarely touch.

Related: Tiny Change, Big Impact: Organize a Small Closet in a Weekend (video)

It turns out that clutter profoundly affects our mood and self-esteem. CELF’s anthropologists, social scientists, and archaeologists found:

• There’s a link between high cortisol levels in female homeowners and a high density of household objects. The more stuff, the more stress women feel. Men, on the other hand, don’t seem bothered by mess, which accounts for tensions between tidy wives and their clutter bug hubbies.
• Women associate a tidy home with a happy and successful family. The more dishes that pile up in the sink, the more anxious women feel.
• Even families that want to reduce clutter often are emotionally paralyzed when it comes to sorting and pitching objects. They either can’t break sentimental attachments to objects or believe their things have hidden monetary value.
• Although U.S. consumers bear only 3% of the world’s children, we buy 40% of the world’s toys. And these toys live in every room, fighting for display space with kids’ trophies, artwork, and snapshots of their last soccer game.

The studies outline the results of clutter, but they don’t always offer solutions. The good news? You can do some simple things to declutter your home and raise your spirits.

Adopt the Rule of Five

Every time you get up from your desk or walk through a room, put away five things. Or, each hour, devote five minutes to decluttering. At the end of the day, you’ll have cleaned for an hour.

Be Ruthless About Your Kitchen Sink

Pledge to clear and clean your kitchen sink every day. It takes a couple of seconds more to place a dish in the dishwasher than dump it in the sink. A clean sink will instantly raise your spirits and decrease your anxiety.

Put Photos Away

Return to yesteryear when only photos of ancestors or weddings earned a place. Put snapshots in a family album, which will immediately declutter many flat surfaces.

Unburden Your Refrigerator Door

Researchers found a correlation between the number of items stuck to the fridge door and the amount of clutter throughout the house. Toss extra magnets and file take-out menus.

Related: How to Organize Your Fridge So You Never Waste Food Again

Test Whether You’ll Miss It

Fill a box with items you don’t love or use. Seal the box and place it in a closet. If you haven’t opened the box in a year, donate it (unopened!) to charity.

By: Lisa Kaplan Gordon