6 signs you need more sleep By Abby Lerner Men's Health Getty Images stock If you feel sick -- and you never get sick -- your immune system may be suffering from too little sleep. Need a reason to hit the snooze button a few more times? Sleep is as vital for survival as food, according to Dr. Mary Susan Esther, president of the American Academy of Sleep Medicine (AASM). And chances are you're more likely to burn the midnight oil to finish all your work (and play) than you are to pass up dinner. But chronic lack of sleep can lead to a host of health problems, such as high blood pressure, obesity, depression, irregular hormone production, a weakened immune system, memory lapses, constant irritability, and decreased concentration and reaction times. So are you spending enough quality time between the sheets, asleep? See how many of the signs below describe you. Then decide if a sleep deficit is holding you back. How to Sleep Right, Tonight You're not hungry for lunch. A lack of sleep can make you constantly want to eat more, or persistently feel like you're not hungry. It throws off your internal clock resulting in abnormal feelings, which is why so many people lose or gain weight during periods of sleeplessness. You've looked at three other Web sites in the last 5 minutes, and checked your email twice. No, you (probably) don't have Attention Deficit Disorder. Whether you're writing a quick email or solving chemical equations; a lack of sleep can make focusing seem impossible. You can't remember where you put the car keys. Your brain needs sleep to refresh and regenerate. Without it, your short-term memory may be impaired, which is why pulling an all-nighter rarely yields better results than getting quality shut-eye, according to Dr. Neil Kline, a sleep physician and representative of the American Sleep Association. Is Sleep Really Necessary? You can't carry on a conversation. Come Saturday night you may work a party like a pro, but as long as you're sleep-deficient, coming up with witty, or even coherent, one-liners is out of the question. You're drowsy at the wheel. Your eyes may glaze over now and then when you're staring at the computer screen or stuck in an endless meeting, but if you struggle to stay awake behind the wheel, or doing any task that puts your life at risk, you're not just bored. You need more sleep. Caffeinated drinks, blasting music, or rolling down the windows (in January) may arouse you briefly, but it won't keep you alert for long drives. You feel sick, and you never get sick. Your immune system repairs and strengthens while you sleep. So in addition to eating flu-fighting foods, log at least seven hours a night to stay healthy all season. Boost Your Immune System Now More Links: Sleep Better Tonight The Cost of Lost Shut-Eye 14 Barriers to Deep Sleep The Cities That Never Sleep