You Stay Up Way Too Late
Whether you're putting in overtime at work or getting sucked into catching up on Game of Thrones, staying up late means you're not getting enough hours of shut-eye. Most people need around seven, give or take, so if you're not getting that, then you'll wake up exhausted and cranky. Sleep deprivation can lead to eating more and can also weaken your immune system — hello, cold! Set a bedtime and stick to it (even on the weekends), and if you have to stay up late, try to sleep in a little in the morning.