This Is How Much Sleep You Actually Need a Night, According to a Doctor

How much sleep you need per night

Stephanie Montes

Too much of a good thing is never a good idea, but deprivation can sometimes be worse. It's all about striking a healthy balance, especially when referring to the amount of sleep you should get every night. Whether you realize it or not, the amount of sleep you get every night can affect everything from your skin to your metabolism. So before you go pressing that snooze button for an hour or, worse, binge-watching that new series into the wee hours of the morning, here is exactly how much sleep you actually need at night, according to Dr. Sunitha D. Posina, a board-certified internist.

Meet the Expert

Dr. Sunitha D. Posina is a board-certified physician in Internal Medicine. She received a Bachelor's degree from Rutgers University in Biology and Economics prior to starting her medical training at the PSI Medical College in southern India. She pursued her post-graduate training in Internal Medicine at Stony Brook University Hospital in Long Island.

How Much Sleep Do You Really Need?

"The average adult should aim to get between seven to nine hours of sleep per night to function best," explains Posina. This goes for any person over the age of 20. "Contrary to popular belief, the hours of sleep you need don't vary as much as you get older."

The average adult should aim to get between seven to nine hours of sleep per night to function best. Contrary to popular belief, the hours of sleep you need don't vary as much as you get older.

But on the other hand, be sure not to get more than 10 hours of sleep every night, as this is considered oversleeping. "People who oversleep tend to experience more anxiety, low energy, and difficulty remembering things," explains Dr. Posina. "Other health issues linked to oversleeping are diabetes, headaches, back pain, depression, and heart disease."

What Happens When You Don't Get Enough Sleep?

When you're not clocking enough zz's every night, you may be putting your health at risk. Here's what can happen if you're consistently getting fewer than seven hours each night.

Lack of Sleep Can Make You Sick

"When the body doesn't get enough sleep, the immune, nervous, endocrine, cardiovascular, and digestive systems suffer," explains Posnia. She explains lack of sleep on a daily basis can weaken your immune system, making it easier for you to get sick. "Someone who is getting below the minimum requirement of sleep may not fend off foreign invaders like bacteria and viruses as quickly as the average person." But aside from the common cold or flu, Posina also tells us that getting less than five hours of sleep each night can raise your blood pressure, increasing the likelihood of developing cardiovascular diseases. 

What's more: sleep also has a direct relationship with appetite, increasing the chances of obesity. "Lack of sleep disrupts the digestive system, increases your appetite, and lowers your insulin tolerance," explains Posina, "which can explain why nighttime snacking, obesity, and diabetes are common side effects."

It Can Affect Your Physical Appearance

There's only so much expensive beauty products can do—the overall appearance of your skin, hair, and nails ultimately comes down to your internal health, including sleep. Insufficient sleep is a form of stress to the body, which can affect many aspects of our appearance. For one, collagen is vital to the elasticity and structure of the skin—it's what gives you a plump, bouncy appearance—but lack of sleep can slow the production. Posina, who also has a certification in dermatology therapies, says, "when collagen slows, signs of aging become more noticeable as the skin becomes less firm." Additionally, she says, "Dull, dry skin is also related to insufficient sleep because of a lack of oxygen flowing through the blood. The lack of oxygen causes the skin to appear pigmented or blotchy." 

Lack of sleep can also produce the stress-response hormone cortisol. Posina says, "an increase in cortisol and focus has been linked to the onset of hair loss." When your body produces the cortisol hormone, it signals the hair follicle to shift out of the growth and cause it to fall out. 

You May Have Less Productivity

Coffee is great for boosting productivity, but no amount of caffeine can compare to a good night's sleep. Posina says getting less than the recommended hours of sleep each night has been known to make a person moody, emotional, quick-tempered, anxious, and even depressed. "Sleep is a crucial aspect of keeping the central nervous system, our brain's main information pathway, functioning correctly—it's harder to concentrate, think creatively, and problem-solve when our brains aren't working at full capacity." She also adds chronic sleep deprivation can negatively affect our short and long-term memory. "While we sleep," she says, "the brain develops connections that help us process and retain new information."

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