The traditional rules about how to be a “real man” in America are breaking down. Economic upheaval has shifted wage earning from men to their wives or partners. The rise of men as primary caregivers of their children is challenging our most fundamental assumptions about gender. The gay rights and trans rights movements are creating expansive new definitions of masculinity. Millennials are leading a much broader acceptance of diversity.

This generation is witness to a collision between traditional masculinity and a new wave, one that values intimacy, caregiving, and nurturing. But many of us have spent our lives under immense pressure to stifle emotional expression of any kind. And we’re learning there’s a cost: Men are suffering higher rates of life-threatening disease, depression, and death. Simply put, the suppression of emotional expression in men is damaging their health and well-being.

If you’ve grown up in the United States, then you’re familiar with the Man Box, the longstanding rules of how to walk, talk, and sound like a man in America:

1. Real men don’t express a wide range of emotions. They limit themselves to expressing anger or excitement.

2. Real men are breadwinners, not caregivers.

3. Real men are “alphas” and natural leaders.

4. Real men are authoritative and make all final decisions.

5. Real men are physically tough and sexually dominant.

These rules take hold early in our lives. Boys 4 and 5 years old are told to shake it off, man up, don’t be a crybaby, and, worst of all, don’t be a girl. This is because the Man Box devalues any form of emotional expression traditionally deemed to be feminine. A devastating result of this anti-feminine bias is that women, gays, and trans people face epidemic levels of bullying, rape, misogyny, homophobia, and violence.

The Man Box robs our sons of a lifetime of opportunities to develop their emotional capacities. Instead, they grow into emotionally isolated men who wall themselves off from the social connectivity central to healing and creating community. The resulting health effects are undeniable.

One in three men aged 45 or older reported himself to be lonely or socially isolated, according to a 2010 survey conducted by AARP. The consequences of that social isolation can be fatal. Between 1999 and 2010, suicide among men aged 35–64 rose by nearly 30 percent, as reported by the Centers for Disease Control and Prevention. Although rates have been rising for both sexes, the study found that middle-aged men are three times likelier than women to end their own lives—27.3 deaths versus 8.1 (per 100,000).

But the risks of social isolation are not just psychological; the absence of robust social relationships has a direct measurable impact on men’s physical health. A 2004 medical study based in Sweden showed that for middle-aged men, having a strong social network and sense of belonging lowered their risk of heart attack and fatal coronary heart disease; inversely, low social support predicted a risk.

The study further confirms that the risk of mortality for poor social relationships is comparable to risk factors like smoking and alcohol consumption, writes Niobe Way, author of Deep Secrets and professor of applied psychology at New York University. “This point underscores the fact that friendships are not simply a feel-good issue—they are a life-or-death issue.”

Add to this epidemic of emotional isolation the physical impact of unresolved trauma in men’s lives, and the combined effects are devastating. In The Body Keeps the Score, psychiatrist and PTSD researcher Bessel van der Kolk explores his decades-long work treating victims of catastrophic trauma. In 1978, he joined the Boston Veterans Administration Clinic as a staff psychiatrist. There, working with veterans of the Vietnam War, van der Kolk began to see the patterns that mark our modern-day understanding of trauma.

How much unresolved trauma do men carry after decades of emotional suppression?

He learned that the human body, when confronted with trauma, can etch horrific memories in the brain, literally reorganizing our perceptions and imagination. The most harmless sounds can trigger flashbacks. One veteran, upon hearing a baby crying, “found himself suddenly flooded with unbearable images of dying children in Vietnam.” He was stuck, in effect, in a terrible loop, revisiting the events over and over again.

One of the many physiological responses to trauma can be seen in a region of the brain called Broca’s Area, which freezes up during flashbacks. This region of the brain is where we construct language to define and interpret our experience of the world. Is it any wonder people find it deeply challenging to put their experiences of trauma into words? Our own physiology is telling us it’s better to remain silent, making trauma all the harder to share or process.

And what exactly qualifies as trauma? Is it only present after catastrophic events or can it also take hold in the smaller brutalities of daily life, on playgrounds or in locker rooms? How much unresolved trauma do men carry after decades of emotional suppression?

I can recall, as a 7-year-old, seeing my home disappear out the back window of a car as a bitter divorce and my mother’s new marriage drew me away. I recall my brother taking out his shock and rage on me for 15 years afterward. I still flash back to the suffocating bullying and violence that ran rampant throughout my years of school and Scouts. And yet, when is any man encouraged to share such stories? For generations, talking about such things was antithetical to our culture’s insistence on male toughness. Thankfully, this is changing. As an editor for the Good Men Project, a website devoted to modern masculinity, I see thousands of men’s stories being told. But we need to hear more. Millions more.

Trauma and the Man Box are mutually reinforcing. If, as men, we do not share our feelings, we will accrue decades of painful hidden stories, some of which will play over and over, triggering depression, fear, and unresolved anger toward ourselves and those we love.

Van der Kolk writes, “Everything about us—our brains, minds, and our bodies—is geared toward collaboration in social systems. This is our most powerful survival strategy, the key to our success as a species, and it is precisely this that breaks down in most forms of mental suffering.”

If we are to empower our sons and improve men’s lives—and their health—we must tear down the walls of the Man Box, encouraging boys and men to express their full emotional range. The path forward begins in our homes. In small, ongoing daily conversations, we can encourage our sons to explore their internal emotional landscapes, sharing those profound discoveries of life. The result will be countless authentic human moments, strung out across decades, each one growing the rich tapestry of human connection and capacity.

The cost of failing to do so is incalculable. Without the robust social networks that emotional expression creates, men will continue to suffer social isolation and shorter, sicker lives.

Van der Kolk defines humans as powerfully resilient and resourceful creatures, able to move beyond the challenging events of our lives and heal. But to do so, men must collaborate, connect, and share our stories, no matter how difficult they may be to tell.

And everyone else? They need to listen.