When we don’t get enough sleep, our brains don’t properly reset for the next day. A night of insufficient sleep won’t cause irreversible damage, but a prolonged sleep deficit can lead to major health issues.

The importance of sleep

“Sleep is a healing mechanism for both [the] mind and body,” says Dr. Sarah Hussain, sleep specialist.

According to Dr. Hussain, sleep is understood to remove toxins our bodies create while we’re awake; to promote brain development and restoration; and to help overall neural function. Sleep also regulates body temperature and boosts the immune system.

A few nights of bad sleep may lead to poor concentration, impaired memory, and slower reflexes. You might also feel fatigued and moody.

And prolonged sleep deprivation can lead to hypertension (high blood pressure), cardiac arrhythmia, diabetes, chronic fatigue, weight gain, and depression. Sleep deficits can also cause a greater risk of dementia and cognitive decline.

So how much sleep should you get? Aim for seven to eight hours a night. More than that, Dr. Hussain warns, can also lead to similar health issues as too little sleep.

“Anything too little or too much is not good,” she says. “Less than six hours and more than nine hours have shown to increase morbidity and mortality.”

Healthy sleep habits 

It’s important to focus not only on how much sleep you get but also on the quality of your sleep. If you can’t fall asleep at night, Dr. Hussain recommends you don’t force it.

“Try to go to bed when you are sleepy,” she says. This is known as sleep restriction, a method often used to treat insomnia. It aims to reduce the amount of time someone spends in bed tossing and turning, which leads to a higher quality of sleep.

The stress from not falling asleep can reduce both your quantity and quality of rest. So, remember: It’s not about being perfect. It’s about building healthy sleep habits.

“You don’t have to go to bed at the same time if you’re not sleepy,” Dr. Hussain says. “But your waking up time has to be the same.”

If you happen to get less sleep one night, there’s nothing wrong with taking a short nap during the day. But Dr. Hussain advises that naps should be no more than half an hour to avoid disrupting your sleep at night.