How much sleep do you need?

Everyone knows that getting the right amount of sleep is critical to functioning well — you know it the moment you wake up in the morning after tossing and turning all night, or when you go to bed way too late.

Proper sleep habits are linked to a strong immune system, a healthy weight and high brain functioning. But what is the right amount for you?

We’ve all been told eight hours is the ideal amount, but according to the Mayo Clinic, the aging process can change how much sleep we need throughout our lives.

Adults should get between seven and eight hours of sleep, and school-age children should get between nine and 11 hours. Toddlers and babies should get the same as older children, plus an additional nap. Babies need three or more hours of nap time, while toddlers can use between two and three hours.

The elderly sleep a little more lightly than younger adults, so they likely need a nap during the day to get the seven or eight hours recommended, according to the Mayo Clinic.

Interestingly, the Mayo Clinic does say you can and should make up missed sleep.

Recent studies have shown that people who do shift work (working outside the normal 9-to-5 hours) for long periods of time can have more memory problems than people who work during the standard work hours. A researcher who looked at the possible correlation said the issues with memory could be tied to stress from the disruption of your body’s rhythm: Sleep at night, active during the day.