Leading Neuroscientist: Stress Leaks Through Skin, Is Contagious, Gives You Belly Fat! Dr Tara Swart

Cortisol, the main stress hormone, leaks from sweat into the air around us and is absorbed through others’ skin. Leaders with chronically high cortisol effectively “bathe” their teams in stress, contributing to inflammation, heart risk, gut issues, and stubborn belly fat that doesn’t shift with diet or exercise alone. Reducing your own cortisol—through aerobic exercise, journaling, therapy, and addressing root causes—is both self-care and leadership hygiene.

The glymphatic system flushes out toxic proteins (tau, amyloid, etc.) associated with dementia via active fluid “jets” during sleep. This cleansing process takes 7–8 hours of real sleep, not just time in bed. Side-sleeping improves this clearance, and insufficient or fragmented sleep impairs memory, emotion processing, and long-term brain health—even if you feel you can “get by” on less.

Sleeping next to a partner increases oxytocin, strengthens emotional bonds, and can even show up as spikes in heart rate variability–measured resilience when partners kiss goodbye early in the morning. Swart warns that “sleep divorce” (separate bedrooms) may erode bonding over time, advocating for co-sleeping whenever practical and compensating with deliberate physical affection and closeness when it’s not.

Neuroplasticity doesn’t end at 25; between 25 and 65 the brain will plateau if unstimulated, but can significantly improve with intense learning and deliberate habit change. Swart’s change sequence: (1) Raise awareness of the pattern and underlying belief (not just the behavior), (2) Focus attention on where it shows up and its consequences, (3) Deliberate practice of alternative thoughts/behaviors in real situations, and (4) Build accountability (friends, coaches, visual boards) so you don’t give up when it’s hard.

Hormones like estrogen, progesterone, and cortisol leak from sweat and entrain others’ cycles and stress levels, while social contagion data show you’re more likely to divorce or become obese if close friends do. Swart stresses curating your “tribe” toward people who are growing, emotionally aware, and kind, because you unconsciously match the psychological level—and wounds—of those around you.