“A ruffled mind makes a restless pillow.”
After doing my research on sleep and longevity, the “I’ll sleep when I’m dead” mentality takes on a whole new level of irony -- mainly because sleep quality is perhaps the biggest predictor of longevity. While there are five total stages of sleep -- involving non-rapid eye movement (NREM) and rapid eye movement (REM) sleep -- today’s article focuses on the importance and improvement of deep sleep, stages 3 and 4, which are your most relaxed, healing and regenerative stages in the course of a night’s sleep.
What Is Deep Sleep & Why Is It Important?
Deep sleep, also known as slow-wave sleep, is the phase during which our most important physiological and regenerative processes take place. It is not the stage in which dreams take place -- that’s during REM sleep -- but deep sleep is critical to maintenance of the brain’s neuroplasticity and sustainable learning efficiency, as shown in this study.
For the average, healthy adult, deep sleep makes up roughly 13 to 23 percent of total sleep each night, and that percentage decreases steadily with age. However, deep sleep promotes the following functions (according to Healthline.com), which are critical to health and longevity:
Processing learning and emotion
Balancing of blood sugar and metabolism
Immune system regeneration
Ways to Improve Deep Sleep
In terms of overall health, wellness and rest, not all sleep stages are created equally. While all five stages are important to recovery and feeling good, it’s possible to sleep the recommended eight hours each night without receiving enough time in deep sleep. This is common for those who experience restless sleep -- sleep characterized by tossing and turning, frequent wakefulness or other disruptive health conditions -- as sleep quality is a better predictor of health than sleep quantity.
In my experience, there are various research-backed habits and methods that have helped increase my deep sleep on a nightly basis, most of which are holistic and require zero medications or other allopathic medical interventions. Here are some research tidbits supporting some of the most effective deep-sleep-promoting practices:
Brainwave Entrainment: As talked about in previous Sonic Yogi articles, such as this one called Three Ways Sound and Music Can Help You Sleep, brainwave entrainment involves synching your brainwave frequencies to rhythms of external stimuli, such as auditory or visual cues. Binaural beats and crystal or singing bowls produce sound frequencies akin to the brainwave frequencies found in meditation or deep sleep, which entrains the brain to achieve these states with greater ease. One study showed that sedative music created by music therapists resulted in reducing the amount of time it took participants to fall asleep, as well as prolonging the duration of deep sleep, measured via polysomnography.
Exercise: According to this systematic review on sleep and exercise, exercise -- especially when done roughly an hour and a half before bedtime -- is associated with increased deep sleep and decreased REM sleep throughout the night.
Yoga: A study published in The Journal of Ayurveda and Integrative Medicine found that a long-term yoga practice correlates with greater sleep quality -- including more deep sleep -- and better quality of life among the elderly. The mindfulness and movement aspects of yoga combine to produce effects similar to both brainwave entrainment/meditation and traditional physical activity.
Sleep Rituals and Routines: Creating a specific nightly routine -- which can involve powering down electronics, dimming the lights at a specific time, steering clear of the bedroom before going to sleep and turning down the thermostat -- can help set the stage for a good night’s sleep. For adults and children alike, sticking to the same routine or ritual every night creates cues for the brain to transition from a state of alertness and wakefulness to one of rest, relaxation and sleep.
Meditation: Regular meditation helps organize sleep-wake behavior. In sleep studies done on vipassana meditators across a wide range of ages, researchers found that vipassana meditators had a significantly different sleep architecture than the control group, which involved enhanced deep sleep and REM sleep, as well as increased total number of sleep cycles per night.
Does Sleep Improve Mental Health?
Sleep and mental health go hand-in-hand. According to this article posted by Harvard Health, sleep disruption affects neurotransmitters and hormones associated with thinking and emotional regulation. While the mechanisms connecting sleep and mental health are not 100% clear -- meaning there is no apparent direct link between a specific brain mechanism, sleep and mental well-being -- poor sleep exacerbates psychiatric disorders and vice versa. The most common mental health problems associated with poor sleep are depression, anxiety disorders, ADHD and bipolar disorders.
All in all, sleep-promoting practices and interventions -- like the suggestions listed above -- can improve your mental resiliency and flexibility when dealing with daily stressors, as well as more serious anxiety, depressive, manic and/or attention-deficit disorders. The relationship between sleep and mental health is inherently complex, but on the most basic level, improvements in sleep contribute to better overall quality of life for people of all mental and physical health signatures.
Sleep and Your Physical Health
Not only is deep sleep important for maintaining mental health, it is also critical for physical wellbeing and immunity. In this study on the effects of sleep on contracting rhinovirus (the common cold), researchers found that participants with less than 7 hours of sleep each night were 2.94 times more likely to become infected than those participants who slept 8 or more hours each night.
Research on sleep and the immune function suggests that it’s slow wave sleep, or deep sleep, specifically, that’s associated with the release of immune regulatory hormones. Notably, the relationship between sleep and immunity is bidirectional, as a healthy immune system releases cytokines that signal the body when it is time to sleep.
Improving Your Deep Sleep
All in all, there is ample research doting the importance and benefit of getting enough sleep -- particularly, getting enough deep sleep. Sleep is a multifaceted process that ties together various aspects of wellness, immunity, mindfulness and overall health. There’s also one thing that’s for certain when it comes to sleep: the more you effortfully try to achieve it, the less of it you’re likely to get.
Experiencing the occasional night of tossing, turning and fruitlessly grasping for sleep is part of the human experience. Psychologically, sleep is one of those things that it pays to pay attention to, but not too closely. Which is why it’s all the more important to incorporate mindfulness practices into the quest for better, deeper sleep, giving you a more holistic approach that indeed improves sleep while also providing more stable, nourishing mental, physical and spiritual foundations for finding ease in all areas of life.
With sleep -- as with every other aspect of living well, in my opinion -- there lies great benefit in both targeting specific problems or challenges, as well as creating larger scale habits, routines and rituals that produce more generalized effects on overall wellness. The point here is to simply bring awareness to the importance of sleep and provide a variety of ideas, methods and information to add to your toolkit for living well. These are a few of the methods that have improved my deep sleep.
Sleep and Sound Therapy
Sound Therapy has also been helpful for improving my deep sleep. Relaxing music and sounds have the ability to help brainwaves begin to cycle down from our normal waking state in Beta mode. Through a process called entrainment, brainwaves can synchronize to the frequencies of music and sound for deep relaxation. Moving the mind toward Alpha and Theta brainwaves, can have an impact on relaxing the mind and body for sleep. In addition, sounds have been shown to help release melatonin, the body's sleep hormone. Read more about this process here: Three ways music and sound can help you sleep.
article by Taylor Goodin with contribution by Sonic Yogi