1. Suntan--Squinting at the sun increases feelings of anger and aggression by up to 44 percent. Your mood and your facial muscles are linked and the way your eyebrows dip and cheek muscles pinch when you squint mimics your expression when angry. So your pissed-off face tricks your brain toward feelings of irritation. The simple solution is sunglasses. Shades totally eliminate squinting and helps your temper in the process.
2. Your coworkers or roommates--Bad moods are contagious. A study found that spending time with ill-tempered friends or coworkers also messes with your mood. When other people discuss your life, job, or surroundings in gloomy ways, your brain can’t resist soaking up that negative feedback. Buy your buddy a coffee. Even if the gesture doesn’t perk him up, committing random acts of kindness will brighten your mood.
3. Other people’s Facebook pics—In a study of Facebook users, 9 percent felt angry, frustrated, or both after looking at their friends’ photos. What's even more surprising is that life satisfaction dropped an average of 15 percent among the picture lookers. It seems that checking out shots of your buddies hiking exotic locales or relaxing on vacation can trigger feelings of envy, misery, and loneliness. Take a look at your own Facebook photos. Revisiting your personal adventures soothes your temperament.
4. Your empty water bottle--Even slight dehydration can dry out your mood. Whether you’re working out or kicking back on your couch, the more thirsty you are, the more your mood worsens. It’s possible that your body detects dehydration and communicates your thirst to your brain’s mood regulators and that leads to crankiness.
(If your urine isn’t plentiful and pale-colored first thing in the a.m., you’re not drinking enough.)