Brushing before bed is not enough. Amount of snooze time is the biggest lifestyle factor, after smoking, that affects oral health. Periodontal disease afflicts people who sleep six hours or less significantly more than those who get seven to eight hours, perhaps due to impaired immune systems.

Is sexual harassment about desire or control? Women who are assertive experience more harassment than their demure counterparts. Men harass women who have masculine traits in order to keep the sexes unequal, especially in male-dominated industries.

Trying to master a mental task? Act it out! You'll solve similar problems better in the future. In a study reported in Cognition, when kids were told to use gestures as they learned to do a type of math problem, the lesson stuck. Embodiment gives you—literally—another way to grasp the problem at hand.

Turning the other cheek can be noble and smart. Unless you have the power to retaliate, forgiveness deters repeated wrongs more than holding grudges does. People are more careful to avoid aggrieving you again if you forgive them the first time, proving leniency is the best policy.

If you're in a position to help someone, you may have to go out of your way to offer your services. Two studies show that potential helpers (say, teaching assistants) overestimate how often people will approach them, because they underestimate how much asking for assistance challenges people's self-esteem.

Twenty-three percent of American adults think American lives are worth more than others'.

Trying to get amped by working out with others in front of a mirror? If you're self-conscious, that's a bad idea—the reflections turn your recreation partners into spectators. Boosting insecurity while getting physical lowers endurance and blunts that sought-after runner's high.