The Science of Quality Sleep
The connection between sleep and health is well-researched by the National Sleep Foundation (NSF). During Sleep Awareness Week, the NSF shares valuable information on how people have been sleeping the past year.
In the 1950s, scientists thought that the brain went into “shutdown” while an individual slept, but it is now known that the sleeping body cycles through regular sleep patterns of activity, also known as the sleep cycle. Approximately every 90 minutes, the body moves through four sleep stages, with the length of each stage varying based on the age of the sleeper. The first three sleep stages are categorized as non-REM sleep, and the fourth stage is Rapid Eye Movement (REM) sleep.
In Stage 1 (Non-REM Sleep 1) of the sleep cycle, the heart rate and breathing slow as muscles begin to relax. This is the lightest stage of sleep, with the brain producing alpha and theta waves. Stage 2 (Non-REM Sleep 2) lasts approximately 25 minutes as the brain creates brief bursts of electrical activity, the heart rate and breathing continue to slow, and the body temperature drops. In Stage 3 (Non-REM Sleep 3), the body begins to fall into a deep sleep where the brain produces slower delta waves. This resting phase allows the sleeper to feel refreshed upon waking and is when the body repairs muscle tissue and improves immune function. Finally, after about 90 minutes, the body enters Stage 4 (REM Sleep), the deepest level of sleep, where Rapid Eye Movement occurs. The brain is highly active in this stage, characterized by dreaming, irregular breathing, increased heart rate and increased blood pressure. Stage 4 (REM Sleep) is critical for learning, memory, daytime focus and mood stabilization.
Sleep is an essential function that contributes to whole-body health and well-being. The National Sleep Foundation recommends the following daily sleep allotment for different age groups.
Age Group/Age Range/Recommended Amount of Sleep Per Day
Newborn, 0-3 months, 14-17 hours
Infant, 4-11 months, 12-15 hours
Toddler, 1-2 years, 11-14 hours
Preschool, 3-5 years, 10-13 hours
School-age, 6-13 years, 9-11 hours
Teen, 14-17 years, 8-10 hours
Young Adult, 18-25 years, 7-9 hours
Adult, 26-64 years, 7-9 hours
Older Adult, 65 years or older, 7-8 hours
The Center for Disease Control and Prevention has labeled insufficient, “unprotected” sleep as a “public health epidemic.” Approximately 70 million Americans suffer from a sleep problem, and 60% of that number have a chronic sleep illness, such as obstructive sleep apnea (OSA). Sleep disruptions can cause significant neurocognitive, cardiovascular, and cerebrovascular impairments. With the help of a physician, identifying common sleep disorders such as sleep apnea, insomnia, hypersomnia or narcolepsy can help sleepers improve energy levels, productivity, and cognitive function.
Sleep apnea is characterized by irregular or interrupted breathing during the sleep cycle, OSA being the most common form. Muscles in the back of the throat cause the airway to narrow and close, thus lowering oxygen levels in the blood and causing the brain to signal the body to wake. Those suffering from sleep apnea can stop breathing hundreds of times each night. Symptoms include feeling tired/fatigued despite sleeping through the night and loud, chronic snoring.
Insomnia is a clinical diagnosis that disturbs an individual’s ability to fall asleep or stay asleep. In more serious instances of the condition, called chronic insomnia, sleep is broken at least three nights a week for at least three months.
Hypersomnia or excessive sleepiness is characterized by regularly feeling groggy or tired throughout the day despite getting a full night’s sleep. Symptoms include daytime drowsiness, anxiety, irritability and unshakable tiredness. This condition is especially dangerous because it can cause accidents while driving or operating machinery.
Narcolepsy is a chronic sleep disorder in which an individual experiences “sleep attacks,” where they fall asleep at unusual or inappropriate times. Symptoms also include difficulty concentrating on normal daytime activities and waking up alert but unable to stay awake for extended periods.
Healthy sleep habits begin before ever pulling back the sheets. Establishing a bedtime routine and incorporating simple lifestyle changes can significantly improve sleep quality and overall feelings of wellness. Going to bed in consistent patterns helps the body synchronize the body’s circadian rhythm or natural sleepwake cycle. Most adults should get seven to nine hours of sleep each night, even on weekends.
We can prepare our bodies for sleep with meditation, gentle stretching or introducing calming scents like lavender, jasmine or vanilla. Avoid eating heavy meals and drinking caffeine or alcohol too close to bedtime, disrupting the sleep cycle. Dimming the lights and removing electronic devices that emit blue light also help to prime the body for sleep. Because screens inhibit melatonin production, it is ideal to have a bedroom free of televisions, tablets, phones and laptops. To drift off to sleep faster, switch to reading your favorite book instead of scrolling on social media.
Oleg Chernyshev, MD, is associate professor of Neurology and Sleep Medicine, LSU Health Shreveport.