Week 12, 4/22: Sleep

                                                                  Circadian Rhythms Shifts with Aging  

Circadian rhythm, the body's innate 24-hour pattern, synchronizes with the Earth's rotation. It encompasses physical, mental, and behavioral routines that adhere to a daily cycle, present across various living organisms including humans, animals, and plants.


Ever pondered why certain flowers bloom during the day and close at night? Or why do you consistently crave lunch or feel the urge to nap at specific times daily? These occurrences stem from the responsiveness of living organisms to their internal circadian rhythms.


In humans, circadian rhythms originate from internal factors like hormones and metabolic processes, alongside environmental cues such as light, darkness, temperature fluctuations, mealtimes, and daily routines.


 These rhythms influence:


Disruptions to the Circadian Rhythm include:


With aging, changes in sleep patterns and the timing of biological functions can occur. Wake and sleep times may shift, as seen in scenarios like recent retirement leading to not getting out of bed until mid-morning or an illness disrupting regular exercise routines. Such alterations can heighten the risk of sleep disorders, cognitive decline, and other health issues due to disturbances in melatonin production and subsequent circadian rhythm disruption. Hormonal and metabolic cycles, typically synchronized with sleep and wakefulness, become disordered.

Additionally, traveling across time zones induces shifts in sleep habits, often necessitating adjustments in food intake and exercise schedules. These modifications further impact melatonin production and subsequently influence circadian rhythm.


How Age Affects Your Circadian Rhythm; 11/16/23 Dr. Rehman https://www.sleepfoundation.org/circadian-rhythm/how-age-affects-your-circadian-rhythm 


Understanding Sleep: What are the 4 sleep Stages & Patterns? 

Sleep constitutes a significant portion of the human lifespan, accounting for approximately one-quarter to one-third of our time on Earth. But what exactly happens when you sleep? When we sleep our bodies go through 4 sleep cycles, each characterized by unique physiological processes. The first 3 stages belong to non-rapid eye movement (non-REM) sleep, followed by the onset of rapid eye movement (REM) sleep.


In the first and second stages of sleep, known as light sleep, the body transitions from wakefulness to sleep. During this phase, heart rate and breathing gradually slow down, while body temperature decreases. It's common to experience muscle twitches as the body relaxes further.


Moving into stage 3, termed delta sleep, slow delta brainwaves dominate. This marks the onset of deep sleep, where cells primarily release growth hormones crucial for the repair and maintenance of bones and muscles. Despite decreased brain activity, deep sleep is associated with fostering insightful thinking, creativity, and memory consolidation.


Stage 4 marks the onset of dreaming as the body enters rapid eye movement (REM) sleep. During this phase, the brain becomes highly active, and rapid eye movements occur. The body then produces chemicals that induce temporary paralysis to prevent us from physically acting out our dreams.

On an average night, an individual will cycle through these four or five stages multiple times, with each cycle lasting between 70 to 120 minutes. The deeper the stage of non-REM sleep, the more challenging it becomes to wake a person up, demonstrating the crucial role of each sleep cycle in promoting restorative rest and overall well-being. 


• Stages of Sleep: What Happens in a Sleep Cycle, Dr. A. Singh, https://www.sleepfoundation.org/stages-of-sleep 


• The science of Sleep: Understanding what happens when you sleep ; John Hopkins Medicine, https://www.hopkinsmedicine.org/health/wellness-and-prevention/the-science-of-sleep-understanding-what-happens-when-you-sleep



                                                                    Impact of Sleep on Brain Health


Sleep plays a critical role in maintaining brain health, impacting cognitive function, memory consolidation, learning, problem-solving, and mood regulation. Adequate sleep is vital for optimal brain function, facilitating improved memory consolidation and learning abilities. Therefore, disruptions in sleep patterns can lead to impaired cognitive function, mood disturbances, and difficulties with memory recall and problem-solving skills. 


Chronic sleep deprivation has been associated with an increased risk of developing Alzheimer's disease, as sleep plays a crucial role in clearing harmful toxins from the brain. Therefore, fostering healthy sleep habits is imperative for preserving overall brain health and mitigating the risk of cognitive decline. Furthermore, sufficient sleep, particularly rapid eye movement (REM) sleep, is essential for the brain's processing of emotional information. During sleep, the brain engages in the evaluation and consolidation of thoughts and memories, with REM sleep playing a significant role in emotional memory processing. Therefore, a lack of sleep, especially REM sleep, can detrimentally affect the consolidation of positive emotional content, thereby influencing mood and emotional reactivity. This disruption in emotional processing has been closely linked to mental health disorders and their severity, including the risk of suicidal ideas or behavior.


Depression, one of the most prevalent mental health disorders globally, affects over 300 million people worldwide. Alarmingly, approximately 75% of individuals with depression experience symptoms of insomnia, underscoring the intricate relationship between sleep and mental health. Alterations in melatonin production, often stemming from disruptions in circadian rhythm due to irregular sleep patterns, can contribute to various health issues such as obesity, weight gain, type 2 diabetes, mood disorders, altered brain function, and heart disease. Therefore, prioritizing healthy sleep practices is not only crucial for maintaining cognitive function and emotional well-being but also for overall physical health and disease prevention. 


Sleep Issues and Sundowning, Alzheimer’s Association, https://www.alz.org/help-support/caregiving/stages-behaviors/sleep-issues-sundowning 

Strategies for Improving Sleep (Sharon/Mari)


There are reliable ways to establish a regular sleep schedule to achieving restful nights and energized mornings:


Optimizing your sleep environment is crucial for fostering restorative sleep. Ensure your bedroom is cool, ideally between 65 to 68 degrees Fahrenheit, and keep it dark and quiet. Consider investing in earplugs, blackout curtains, or a white noise machine to minimize disruptions. Disconnect from electronic devices, including phones and laptops, at least an hour before bedtime to reduce exposure to blue light, which can interfere with melatonin production. Maintaining a cooler environment in the evening can help stimulate melatonin release, facilitating easier sleep onset and alignment with your internal body clock.


Be mindful of your lifestyle choices, as they can significantly impact sleep quality. Limit caffeine and nicotine consumption after 2 pm and reduce screen time before bed to minimize stimulation. Avoid heavy meals and excessive alcohol intake close to bedtime, as they can disrupt sleep patterns and diminish sleep quality. Incorporating regular exercise into your daily routine, ideally outdoors for exposure to natural light, can promote better sleep and overall well-being.


If you find yourself needing to nap during the day, aim for short, 20-minute naps to prevent interference with your nighttime sleep schedule. However, if you continue to experience persistent sleep difficulties that affect your health and safety, it's essential to seek guidance from a healthcare professional. Your doctor can offer personalized advice, identify any underlying conditions contributing to your sleep troubles, and recommend appropriate treatments to help you achieve restorative sleep and improve your overall well-being. Remember, prioritizing sleep is an investment in your health and vitality, so don't hesitate to seek support if needed.


20 Tips for How to Sleep Better, Updated 12/8/2023, Dr. A. Singh; https://www.sleepfoundation.org/sleep-hygiene/healthy-sleep-tips