If I don’t get  a good night’s sleep, my mood is bad, my cravings are rampant, and I have no concentration. Plus it’s bad for my long-term health: A good night’s sleep isn’t just about feeling alive the next morning, hitting the ground running or staying alert in your 8 am meeting. If you skip the restorative 7 to 9 hours experts advise, you can increase your risks of a host of ills—from catching the flu to developing heart disease and diabetes. If you’re not getting as much as you need, here are a few health consequences that will have you rethinking bedtime as per the experts:

1. You crave junk food

Too-little sleep may throw off hormones that regulate appetite, increasing a taste for high-fat, high-carbohydrate foods and causing you to want more calories than your body needs. After going without enough sleep for 2 nights, people in one study had more of the hunger-inducing hormone ghrelin and less of the appetite-suppressing hormone leptin.

Over time, this can lead to weight gain. In studies of identical twins, University of Washington researchers found that those who logged 7 to 9 hours a night had an average body-mass index of 24.8—almost 2 points lower than the average BMI of those who slept less.

2. You become a germ magnet

People who get less than 7 hours per night are 3 times likelier to catch a cold, according to a JAMA study. Other research found that sleep-deprived men failed to mount the normal immune response after receiving flu shots. They had only half as many disease-fighting antibodies 10 days after the vaccination, compared with men who were well rested. That’s because sleep boosts immunity; too little impairs it.

3. You’re less able to metabolize sugar

It’s the fuel every cell in your body needs to function. After just 6 days of sleep restriction, people develop resistance to insulin, the hormone that helps transport glucose from the bloodstream into the cells, say University of Chicago researchers. In another study, tests showed that participants who slept fewer than 6 hours a night and claimed to be “natural short sleepers” couldn’t metabolize sugar properly. This could lead to type 2 diabetes, a serious, on-the-rise chronic condition.

4. You’re in a never-ending stress storm

The University of Chicago study also found that inadequate shut-eye caused levels of cortisol, the stress hormone, to spike in the afternoon and evening—increasing heart rate, blood pressure, and blood glucose and raising the risk of hypertension, heart disease, and type 2 diabetes. Aside from posing future health problems, the cortisol-induced alertness comes at an inopportune time—when you should be winding down your day or sleeping.

5. You’re in a foul mood and your brain feels foggy

After a restless night, your reaction time decreases, making driving (among other activities) dangerous. Chronically tired people are also less happy. “Sleep and mood are regulated by the same brain chemicals,” says Joyce Walsleben, PhD. This can raise the risk of developing depression, but probably only for those already susceptible to the illness.

6. You look older

As anyone who’s pulled an all-nighter can attest, the consequences—pasty skin and dark circles—aren’t pretty. “Even worse, increased cortisol levels may slow collagen production, promoting wrinkles,” says Jyotsna Sahni, MD, a sleep medicine doctor at Canyon Ranch in Tucson.

On the flip side, there’s a good reason they call it beauty sleep. “Hormonal changes boost blood flow to the skin, brightening it overnight,” says Melvin Elson, MD, a clinical professor of dermatology at Vanderbilt School of Nursing. Skin temps are higher, too, so age-fighting potions seep deeper for better results. And even though you’re resting, your skin is hard at work. Studies show that cell turnover is 8 times faster at night, softening wrinkles.

5. You’re in a foul mood and your brain feels foggy

After a restless night, your reaction time decreases, making driving (among other activities) dangerous. Chronically tired people are also less happy. “Sleep and mood are regulated by the same brain chemicals,” says Joyce Walsleben, PhD. This can raise the risk of developing depression, but probably only for those already susceptible to the illness.

7. You feel achy

It’s no surprise that chronic pain (like that from back problems or arthritis) can make you toss and turn. But getting too little rest can cause or intensify pain, creating a vicious cycle. In one study from the Johns Hopkins Behavioral Sleep Medicine Program, director Michael Smith, PhD, awakened healthy young adults for 20 minutes every hour during an 8-hour period for 3 days in a row. The result: They had a lower pain tolerance and suddenly developed more pain during a lab test that exposed them to a cold stimulus.

8. You have a higher cancer risk

Exercise helps prevent cancer, but getting too little shut-eye may cancel out its protective effect, concludes a new Johns Hopkins Bloomberg School of Public Health study. Researchers tracked nearly 6,000 women for about a decade and found that workout buffs who slept 7 or fewer hours per night had a 50% greater chance of developing cancer than exercisers who got more Zzzs—similar to the risk of nonexercisers.

Insufficient sleep may cause hormonal and metabolic disturbances linked to cancer risk, erasing the benefits of exercise.