You probably know you feel grumpy when you are tired, but a study carried out by researchers at the University of California, Berkeley, in the US, found just how intense your bad mood can be when you are sleep deprived: You are over 60 percent more reactive to emotional situations when you don’t get enough sleep. Why? Sleep deprivation affects the part of the brain responsible for keeping irrational thoughts and behaviours in check. To keep from blowing your stack without due cause, aim for at least eight hours of shut-eye a night. If you are not able to catch enough sleep, try to avoid or reschedule scenarios that could push you over the edge the next day, like big conversations or fights with your significant other before bedtime.