why are some people grumpy when they're tired?
399028
Because they just want to rest, yet you keep bothering them.
1074610
Sometimes, by the way we live, lack of sleep, poor eating choices, etc. Sometimes we're just hypochrondriacs stressed out for nothing. More often, it's not our fault.  It's bacteria, diseases & hereditary.
17567
Yawning is one of those bodily mysteries that scientists haven't completely figured out yet.  The best theory I could find was that you yawn because you're not getting enough oxygen to the brain (maybe there is a lack of oxygen in the space you're standing).  Whenever you're aware of someone yawning, it activates a reaction in your subconscious mind that acts as a threat response.  Basically, whenever you see someone yawn, it makes you body think there is a shortage of oxygen too, and you yawn in response.  No one knows if this is actually the case, but I think that it is a good theory.
433222
because they make one tired so then they person that isn't tires suddenly becomes tires and yawns. but yawns shouldn't make one another person yawn because the person is just releasing co2 from their bodies.
482096
maybe cause they are not truely happy..
648015
They're trying to change you. It's common for people to try to get under your skin if you're too calm and serene. I don't know why. It's like having an itch. you just have to scratch it.
914926
I think sometimes they are defensive to a point of irrationality.  My guess is that it's not  on purpose but rather it's become a habit!  I think that when you feel different you are different...usually because you want to break the patterns that annoy you about you!
537048
Because according to psychology, they are sympathetic responses.  Its funny that in a test, people who didn't yawn after seeing others yawn were found to be anti-social.
1170939
From what I've read, we are not sure exactly why that happens, but many doctors and scientist believe is is due to a mental reaction that sees a person yawn and believes you should do so as well.  Yawning is a response to a lack of oxygen in the brain under idle conditions, such as standing around or sitting in a chair.  So when you see someone yawn, your brain triggers a yawn to make sure you are also not starving your brain.
785347
They're trying to get on your nerves and annoy you. If someone does this, try rolling your eyes at them, it usually gets them back and makes them feel stupid and immature.
1049703
Good question!\nMany people believe that we yawns are the cause of to get rid of extra carbon dioxide and to take in more oxygen. Not entirely true (see ref 1 and 3). Sometimes we yawn as we shift phases from being awaken, to feeling sleepy, and anytime during our awakened state. And sometimes they simply are contagious(2).\n\n"Giving people additional oxygen didn't decrease yawning and decreasing the amount of carbon dioxide in a subject's environment also didn't prevent yawning. "(3)
1077966
There's alot of reasons for people to be depressed, what really matters is if its a long or short term thing n if it happens more then once in a week.\nEvery answer in this room is a possible reason for depression. Maybe they're going through emotional stuff in their life, they're not getting enough sleep, they may be preg. and a chemical inbalnce may be taking place in the brain.\n\nFirst, people should relieze that other people dont chose to be depressed. Infact, depression doesn't only effect how people act in life but how they sleep at night. Just because someone takes anti-depressants doesn't mean they're trying to kill themselves.\n\nIn The End of it all:\nNo one gets truely upset for no reason and you shouldnt put it that way. To them, they have a reason to be upset, even though you dont see it. Maybe they just need someone to talk to.
1152095
Maybe your just really tired.
285326
Tiredness is not an issue over which you should bury your head in the covers. Actually, fatigue, the tiredness most people feel on a daily basis, is the first symptom of all degenerative disease.\n\nIf you wake up tired in the morning, lack the energy to make it through the day without a stimulating pick-me-up (“don’t talk to me until I’ve had my morning coffee”) and you haven’t got the energy to exercise or even walk from the couch to the TV set to change the dial, then your get up and go has gotten up and gone. You may even be headed for chronic fatigue syndrome or fibromyalgia.\n\nMany people think it’s natural to feel tired. Although it may be common, it's not natural. As a matter of fact, you can have stimulant-free, vibrant, sustained energy - naturally. And, it’s simple. The solution is optimum whole food nutrition. A well-nourished body always has more than enough buoyant vibrant energy. Period. \n\nResearch into the causes of fatigue has been going on for decades. We know you need certain nutritional factors that are not only missing from most people’s diets, but, ironically, they’re consistently being removed from our food supply during processing. \n\nWhy? Because they involve oils and other lipids. If you expose lipids to processing, light and air, they oxidize, become rancid and turn into trans-fatty acids. In other words, they’re sensitive and have a short grocery store “shelf life.” But just because they can spoil in your bread, cereal, rice and pasta, doesn’t mean you don’t need them on a daily basis. You desperately do need them!\n\nJust like a chain is only as strong as its weakest link, your body is only as strong as its weakest cell. Each one of your 73 trillion cells is a link vitally important to your health. They have a job to do and in order to do it, they need certain specific essential lipids. During your daily routine, cells use these lipids to perform a multitude of functions. Just like your car needs gasoline, you need these essential oils. They help to recharge your body’s battery
992868
BECAUSE THEY ARE MISERABLE THEMSELVES AND DON'T KNOW ANY BETTER. JUST LAUGH BECAUSE THERE IS A STRONG POSSIBILITY THEY FEEL THREATENED BY YOUR WORK SKILLS.
676873
I think it is because you body is not functioning at its best when someone is tired.  So what happens is the person's resistance drops and his ability to warm up.  \nHave you ever noticed that after eating you get cold?  It's because your body is working harder to digest the food and the other bodily functions slow down.  That's also why we feel tired after over-eating.
1177413
I depends what made us think that we are going to enjoy and what pissed us off. Generally you will get off mooded more in case you hold someone else responsible for this situation for yours. 'Why does this happen to me ?' is the thought which makes us suffer more than the reality. Your moods are largly in your own hands and you whould seldom give that key to anyone else.