Your social media “friends” may influence how much you exercise. MIT researchers recorded the daily exercise patterns and social network ties of more than $1 million people, finding a person’s Facebook and Twitter connections influenced how much they worked out. Men were influenced by both their male and female friends, while women were only influenced by other women. The findings suggest social influence may be a way to encourage health-related habits.

The American Academy of Sleep Medicine says school should start later for middle and high school students. The group recommended classes start no earlier than 8:30 a.m., which they say will cut down on tardiness and give teens a chance to get enough sleep. A spokesperson says starting any earlier interferes with a young person’s sleep cycle, which could contribute to a host of health problems.

And finally, salty snacks aren’t making you thirsty after all. Researchers tested two separate groups, giving them identical diets except for the amount of salt the ate. The results, published in the Journal of Clinical Investigation, found a salty diet caused test subjects to drink less and eat more. It appears salt triggers a mechanism in the kidneys to hold onto water and contributes to a process which eats up energy, causing hunger and not thirst.