Decoding the Mysteries of Sleep Across the Human Lifespan

March 10, 2024

by Cathe Friedrich

Sleep is a vital part of maintaining both physical and mental health, yet too many people skimp on sleep or overlook its importance. But did you know that sleep also changes with age or that it can even affect your appetite? Let’s explore some surprising facts about sleep and how it affects your health and well-being. You’ll also discover surprising facts about sleep you might not know.

Sleep Architecture and Brain Waves Change with Age

Scientists break sleep down into several stages, each marked by distinct types of brain waves. The two main phases are rapid eye movement (REM) sleep and non-REM sleep. Non-REM sleep is further divided into three stages: N1, N2, and N3 sleep.

In early and middle adulthood, deep N3 sleep accounts for about 20% of the night. However, by age 70, this restorative slow-wave sleep may disappear completely.

Furthermore, older adults tend to have more arousals and time spent awake at night. While children may spend over 50% of the night in deep sleep, that number declines to just 5-10% in those over sixty-five.

Sleep is one of those things that looks drastically different at various life stages. As we get older, our sleep patterns and needs evolve. Understanding those natural shifts can help doctors provide better, more tailored advice for addressing sleep issues at different ages.

Take older adults, for instance. With age, it’s tougher to stay asleep through the night without waking up. Daytime napping also becomes more common. So, when elderly patients visit their doctor complaining of insomnia or feeling unrested, the recommendations might be a bit different than a younger person.

Instead of just prescribing sleep meds, their physician may suggest adopting certain “sleep hygiene” practices to maximize their sleep time and efficiency. Things like sticking to a regular bedtime routine, creating a quiet, comfortable sleep environment, avoiding screen time before bed, and getting morning sunlight.

These lifestyle adjustments can work wonders for helping seniors fall asleep more easily, so they get better quality rest. Of course, what works for a 70-year-old may not be the best solution for a new parent struggling with fragmented sleep. But being aware of how sleep evolves allows doctors to dispense more relevant, age-appropriate guidance.

Having a solid understanding of sleep patterns through the years is key to pinpointing and resolving problems more effectively at every stage of life.

The Link Between Sleep and Body Weight

An emerging body of research shows a bi-directional relationship between sleep and body weight. Both insufficient sleep quantity and poor sleep quality are linked to an increased risk for weight gain and obesity. This weight gain comes from complex hormonal and metabolic changes caused by sleep loss.

For instance, not getting enough sleep impacts the levels of two key appetite-regulating hormones: ghrelin and leptin. Ghrelin is the “hunger hormone” that signals hunger to the brain. Leptin is the “satiety hormone” that tells the brain when the body is full. Chronic sleep deprivation causes a drop in leptin and a rise in ghrelin, boosting appetite.

Furthermore, lack of sleep alters the circadian rhythms that control metabolic function. Staying up late and eating at abnormal hours can influence fat storage. Additional factors like increased opportunities to eat and loss of energy to exercise also play a role.

The Brain’s Waste Removal System Ramps Up During Sleep

The glymphatic system is the brain’s unique process of clearing away metabolic waste products and toxins. This waste removal system relies on cerebrospinal fluid (CSF) to flush toxins from the brain and into the circulatory system for eventual removal from the body.

Fascinatingly, the glymphatic system appears to be far more active during sleep as compared to the waking state. PET imaging scans show that the brain’s interstitial space expands by over 60% during sleep. This expansion allows for increased CSF circulation and a 10-fold rise in waste removal.

One critical waste product cleared by the glymphatic system during sleep is beta-amyloid – the peptide accumulation of which is a hallmark of Alzheimer’s disease. As we age, glymphatic function appears to decrease. Ensuring sufficient sleep quality and quantity as we get older may therefore be key for preventing decline in brain health. Some research suggests that sleeping on your side helps the glymphatics function better.

New Theories on the Possible Functions of Dreams

Who isn’t intrigued by dreams? Yet their purpose and why we have them is still a mystery. Scientists have theories as to why we dream though.

First, dreams may facilitate memory consolidation and integration. During REM sleep, the stage when vivid dreaming occurs, your brain consolidates the information you learned recently and transfers it into long-term storage. Dreams may weave this new material into the tapestry of older memories.

Additionally, some researchers propose that dreams aid in processing emotions. The content of dreams often centers on emotional themes and unresolved tensions. By simulating emotional scenarios, dreams may allow the sleeping brain to regulate mood and manage stress.

Finally, dreams may contribute to creative problem-solving. The bizarre and unconstrained nature of dreams provides an ideal environment for forging new and imaginative connections between disparate ideas. Scientists have devised experiments to test if dreams can incubate solutions to vexing problems.

Though speculative, these emerging theories offer intriguing possibilities regarding the age-old mystery of why we dream.

Sleep Paralysis – A Frightening but Harmless Phenomenon

Have you ever woken up feeling frozen in place, incapable of moving a muscle? This frightening experience is known as sleep paralysis. About 8% of people will experience sleep paralysis at some point in their life. Thankfully, while extremely unsettling, single episodes pose no health risk.

Sleep paralysis usually occurs as you transition from wakefulness to REM sleep. During REM, your brain tells your muscles to not contract to avoid acting out your dreams. So, you enter where your muscles are paralyzed. With sleep paralysis, the brain awakens while the body remains in this paralyzed state.

People who experience this struggle to move their limbs and suffer with pressure on their chests. Some experience vivid hallucinations of intruders or seeing supernatural beings during such a state. Episodes typically last less than a couple minutes but can persist for up to 10 minutes.

Though they aren’t harmful, frequent bouts of sleep paralysis can be a sign of an undiagnosed sleep disorder. Triggers like sleep deprivation, stress, and irregular sleep schedules may cause episodes of sleep paralysis in people who are susceptible. Improving sleep hygiene helps prevent recurrence in most individuals. However, consulting a sleep specialist is the best idea if episodes resist lifestyle changes or cause distress.

Conclusion

Our relationship with sleep evolves across our lives, from the long naps of infancy to the light, fragmented sleep of old age. Appreciating these changes, along with the impacts of sleep on cognition, weight, and health, shows how important it is to prioritize sleep at every age. Paying attention to sleep quality and patterns allows us to identify issues early and intervene when necessary. Sweet dreams!

References:

“How Sleep Works: Understanding the Science of Sleep.” 23 Oct. 2020, sleepfoundation.org/how-sleep-works.
“Sleep Physiology – Sleep Disorders and Sleep Deprivation – NCBI Bookshelf.” ncbi.nlm.nih.gov/books/NBK19956/.
“Sleep paralysis: Causes, symptoms, and treatments.” 20 Oct. 2023, health.harvard.edu/diseases-and-conditions/sleep-paralysis-causes-symptoms-and-treatments.
“The Sleeping Brain: Harnessing the Power of the Glymphatic System through Lifestyle Choices.” 17 Nov. 2020, ncbi.nlm.nih.gov/pmc/articles/PMC7698404/.
“Glymphatic Dysfunction: A Bridge Between Sleep Disturbance and Mood ….” 07 May. 2021, ncbi.nlm.nih.gov/pmc/articles/PMC8138157/.
“Glymphatics: Keeping the Brain’s Waste Removal System Healthy.” 06 Aug. 2018, https://www.wellnessresources.com/news/glymphatics-keeping-the-brains-waste-removal-system-healthy.