Generally held wisdom states that if you want to get enough sleep each night, then you need to get eight hours. And, according to the CDC, this is more or less true. Adults 18 to 60 should aim for seven or more hours a night, while adults between 61 and 64 need to get between seven and nine hours specifically. As people age past 64, eight hours is the most they technically need per night, with seven hours being the least they should get.
These recommendations are based on a person’s 24-hour cycle, which is handy for those who may not work or live on the typical daytime schedule. As long as a person can get seven to nine consecutive hours of sleep every 24 hours, they should be getting a healthy amount of sleep.
But good sleep isn’t just about the amount of time a person spends snoozing. It’s also about how long they spend in each phase of sleep. This is because each phase has its own purpose and benefits. And when it comes to deep sleep, there are serious side effects to missing out.
It affects memory and mood
The amount of time a person should spend in each phase of sleep isn’t a hard and fast rule. Rather it’s an overall percentage of the amount of time they’re asleep. The Sleep Foundation states that between 13 and 23% of a person’s time asleep should be spent in the deep sleep stage, also known as stage 3 or slow-wave sleep.
If a person is getting seven hours of sleep a night, the Foundation goes on to say, that means that 55 to 97 minutes of it should be in deep sleep. So roughly an hour to an hour and a half. And that’s not a number people should be skimping on. Deep sleep is when our bodies re-energize. It is also when our brains work on memory and cognitive function, and enhance motor function, learning, and brain development. In short, it’s when our brains process all the input we’ve gathered throughout the day.
And there are consequences for not giving the body and mind enough time for all of that. As WebMD explains, a lack of deep sleep can lead to an increased appetite with a decreased sense of fulfillment when eating. It can also make a person irritable and less able to focus. Bustle adds that slow reaction time and poor memory are also signs that someone isn’t getting enough deep sleep, making it all the more clear why deep sleep is important.
