Hate Mondays? Afraid of public speaking? Science can back you up.

You wake up in the morning to the sound of your alarm going off, and already, you can feel your blood pressure rising. By the time you arrive at the station—just in time to see your train pulling away—you know you’re in for a bad day.

It’s not all in your head. Here are five things you always knew stressed your mind and body to the max, and now there are studies to prove it.

Most Americans get enough sleep on the weekends, but on weeknights, they average less than seven hours of sleep. Forty-three percent of people between the ages of 13 and 64 say they rarely or never get enough sleep on weeknights. For most people, the shock to your system of going from well-rested to sleep-deprived happens on Mondays.

When the body is sleep-deprived or otherwise acutely stressed, it raises blood levels of cortisol, a stress hormone. A little bit of cortisol is a good thing: It wakes you up in the morning and helps you concentrate at work. But too much raises blood pressure, disrupts concentration, damages memory, and makes you vulnerable to infection.

For people who already have a heart condition, like high blood pressure or hardening of the arteries, this extra stress can be what pushes them over the edge.

One study found that among working people, there’s a 33 percent increase in heart attacks on Mondays. The difference is even more pronounced around the spring daylight saving time (DST) shift, with a massive spike on the Monday morning of DST, and lingering effects for a full week after.

Another study found the same peak in heart attacks on Mondays, with smaller increases on the weekends, possibly due to drinking.

Commuting also gets your stress levels up. Stress levels tend to be highest in situations where there are real consequences for failure—such as being late for work—but you have little or no control, such as waiting for a late train or being stuck in heavy traffic.

Commuters with high stress suffer poor sleep quality, worse mental health outcomes, and more absences from work due to sickness. And the longer your commute is, the higher stress levels get; the average American commute is 25 minutes.

Long commutes affect not just you, but also your loved ones. One study found that long commutes can even raise divorce rates.

Those who walk or bike to work are free from some of the stresses that plague drivers and public transit riders. In fact, one study showed that the more they exercised, the less stressful they found their commute to be.

Learn the Science of Sleep and Why You Need 7-8 Hours »

A study of accountants during tax season provides a perfect snapshot of how deadlines affect stress.

Researchers compared the accountants’ stress levels during tax season to their levels during other times of year. After controlling for their weight, exercise level, diet, workload, and any non-work stresses, they still found that the accountants’ cholesterol levels and blood clotting speed rose dramatically during tax season.

Another study found that having a high-pressure deadline at work is associated with a sixfold increase in heart attacks during the next 24 hours. Although this effect wasn’t shown to be chronic, a different study found that long-term stress at work also increases your blood pressure.

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A famous Gallup poll found that Americans fear public speaking more than heights, spiders, and getting shots. Public speaking was the number two fear, after snakes. One small study found that people would rather give themselves little electric shocks than deliver a five minute speech about their personal qualities.

It isn’t only stress levels that rise before public speaking. That feeling of butterflies in your stomach? It’s not just nerves—the entire nervous system changes how it processes pain in the gut. The immune system also over-activates, scrambling to find an infection that isn’t there.

But it isn’t the performance itself that causes these problems, it’s the fear of public speaking. Another study found that stress levels and blood pressure are elevated before public speaking, but not during or after. It’s own our anxiety tripping us up.

Here’s How to Get Over Your Fear of Public Speaking »

Dr. Terri Orbuch ran a study on married couples that spanned more than 25 years. She found that husbands who had a good relationship with their in-laws were 20 percent less likely to divorce than those who got along poorly. However, the opposite was true for wives. Women who had a close relationship with their husband’s parents were 20 percent more likely to divorce.

Another study confirmed Orbuch’s finding for husbands, but found that if wives initially got along poorly with their in-laws, they were less likely to divorce later in the marriage.

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