Tossing and Turning at Night? How to Get More Deep Sleep

The average person spends around a third of their life sleeping. Yet as many as 70 million Americans suffer from chronic sleep disorders and wakefulness, studies have found, and tossing and turning at night can hinder daily functioning. Researchers believe one of the most important stages of sleep is the third phase of non-rapid eye movement sleep. NREM is the period of deep sleep when heartbeat and breathing slow to their lowest levels, which a person needs to feel refreshed in the morning. Without this, we can't form or maintain the pathways in the brain that allow us to learn and create new memories. Insomnia can also make it harder to concentrate and respond quickly. People who don't get enough deep sleep can develop symptoms of depression, seizures, high blood pressure and migraines. It can even impact immunity, increasing the likelihood of illness and infection. Newsweek asked experts how much deep sleep we actually need and how to get it.

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What Is the Difference Between 'Sleep' And Deep Sleep?

There are two basic types of sleep: rapid eye movement and NREM, the latter of which is comprised of three stages. University of Oxford neuroscience researcher Lukas Krone told Newsweek: "While we sleep, we cycle through different sleep stages. Each sleep cycle lasts about 90 minutes and consists of lighter and deeper stages of NREM as well as rapid eye movement REM sleep. "We typically refer to the deepest stage of non-rapid eye movement sleep as 'deep sleep.' During this phase, it is most difficult to wake someone up. The electric activity of the brain shows characteristic slow waves and our brain performs important restorative processes."

Sara Mednick, a professor of cognitive science at the University of California, Irvine, told Newsweek: "The truth is that there is no scientific definition for deep sleep, but people use it to refer to slow-wave sleep, which is the stage of sleep that is considered the most restorative." Nature describes SWS as phase 3 of NREM sleep—the deepest phase, characterized by delta waves in the brain. Mednick, author of the new book The Power of the Downstate, added: "During SWS, our bodies repair and build muscle tissue, clear out toxins from the brain and strengthen long-term memories, among other functions. None of these functions happen during any other stage of sleep."

How Much Deep Sleep Do You Need?

The amount of sleep that a person needs varies significantly with age. Babies need as much as 16 to 18 hours each day, something that may boost growth and development, especially of the brain. By adulthood, most people need between 7 to 8 hours of sleep a night, but only a small amount of this time is spent in deep sleep. The Sleep Foundation explained that we spend the most time in deep sleep during the first half of the night, adding that during early sleep cycles, SWS commonly last for 20-40 minutes. As a person continues to sleep, it said, this and other NREM stages get shorter, with more time spent in REM sleep instead. A study published in 2006 indicates that people should spend between 13 and 23 percent of their sleep in deep sleep. For an adult getting seven hours, this is between 55 and 97 minutes. For nine hours, it's between 70 and 124 minutes. Mednick also said the amount of SWS required depends on the individual. "This varies by how sleep-deprived people are. The more sleep-deprived, the more SWS they will need. But generally, people need between 2 to 3 hours," she said. Krone added: "There are also healthy and functional 'short sleepers' and 'long sleepers' outside this range. Short sleepers tend to sleep deeper. Our brain can to some extent compensate for reduced sleep duration by increasing sleep depth."

Why Do We Toss and Turn?

Even healthy sleepers change their sleeping position and briefly wake several times each night but cannot remember doing so the next morning, according to Krone. "Patients with insomnia wake up and turn more often and are often aware that they woke up repeatedly throughout the night. There are also sleep disorders that can cause twitching arms and legs—for example, restless legs syndrome," he added. After the age of 60, people tend to sleep more lightly and for shorter periods punctuated by waking. Mednick explained that this impacts the amount of deep sleep we get. "As we age, we lose both the deepest part of SWS, the slow waves, and we lose parasympathetic activity [responsible for functions that conserve the body's natural activity] as well," she said. "It is not clear whether this loss is inevitable or mostly due to increases in stress and the loss of activities that promote deep sleep like exercise, exposure to light, good nutrition, that keep arousal high and makes it difficult for people to get into the deepest sleep." According to the Neurodevelopmental Institute of New Hampshire, many people get less sleep than they need because they are working longer work hours and can access round-the-clock entertainment, believing they can catch up on sleep at other times. The Sleep Foundation also pointed to stress as a potential cause of loss of deep sleep. Conditions such as schizophrenia and Alzheimer's disease can impact SWS too, it added. Krone said: "Substances such as caffeine or the metabolites of alcohol make sleep more fragmented and can prevent us from getting enough deep sleep." Another common cause for losing deep sleep time is obstructive sleep apnea, he explained. "As muscles, including those in our throat, relax when we sleep deeply, the upper airway collapses in patients with obstructive sleep apnea whenever they enter deep sleep. "In response to the lack of oxygen, the patients briefly wake up or enter a lighter sleep stage in order to breathe, so they lose a lot of deep sleep and are therefore sleepy and less able to perform well during the day."

How to Get More Deep Sleep and Avoid Tossing and Turning

Mednick said there were many actions people could take to get more deep sleep or SWS. "The best one is going to bed early and keeping that bedtime consistent. The timing ensures that you get enough deep sleep and the consistency helps your brain form the habit of getting sleepy at the same time every night." She added that older adults who exercise and have good nutrition are more likely to maintain both SWS and parasympathetic activity. A 2016 study found that a diet high in saturated fats was associated with loss of SWS. Krone has three tips for getting more deep sleep: "Avoid caffeine, alcohol and other substances that disturb sleep. Create a quiet and pleasant sleeping environment and reduce the amount of time in bed compared to actual sleep time. Spending excessive time in bed makes sleep lighter and more fragmented while sleep restriction makes sleep deeper and more consolidated." He added that if your partner observes interruptions of your regular breathing pattern during sleep, if your legs feel restless or twitch when falling asleep, or if sleep problems affect your daytime function, you should seek medical advice to identify potential sleep disorders.