The Science of Sleep

Episode 25 - The Science of Sleep
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This episode continues education on self-management of fibromyalgia and other chronic pain conditions. Sleep and rest are an important part of your well-being. Proper sleep is also essential for healing if you have autoimmune diseases, like lupus or RA, or other chronic disorders.

Emerging science shows that sleep is the most effective thing we can do to reset our brain and body health each day.  SLEEP IS NOT THE OPPOSITE OF WAKEFULNESS.  Sleep is an essential physiologic state that is required for health and longevity. Some body functions only occur when you sleep. This episode is about sleep, why we need sleep, how much, and the terms you often hear, such as the sleep cycle (non- REM and REM sleep), the circadian rhythm, melatonin, and of course, the caffeine and why it disrupts our sleep. 😴

You can see the full transcript:https://www.buzzsprout.com/1890983/10875415

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Transcript

Welcome back to Mind your fibro podcast, episode #25  The science of sleep

Today we are shifting from nutrition and starting the discussion on the importance of rest and sleep. I actually think food, fatigue, and sleep are very closely related. Studies suggest that sleep deprivation is associated with increased hunger (especially cravings for snacks and sweets). Poor sleep alters ghrelin and leptin balance, leading to a change in appetite. Appetite hormones become unbalanced, promoting overeating and obesity. The insulin/blood glucose system, your metabolism) is disrupted, promoting insulin resistance and weight gain. 

When we are sleep deprived or physically or mentally fatigued, we tend to make poorer eating choices and to eat more comfort foods and things that our brain perceives as a way to increase energy, like coffee, chocolate, and simple carbs. When the brain is tired, it loses inhibition and starts lacking control over the decisions. Also, the nutrient brain uses for energy is glucose. When we are mentally or physically tired but not hungry,  the brain may perceive fatigue as lacking energy or nutrients, so it's not surprising that we crave foods that eventually convert to glucose, such as simple carbs. But there is another component to fatigue and eating, our habits. If we are too tired to participate in activities, we may get FOMO, or fear of missing out, regret, and may start buffering our feelings using food. We may also have a ritual of what we eat or drink when we are mentally or physically exhausted - it can be a cup of coffee in the afternoon, a diet coke at 3 pm, or a glass of wine after a stressful day of work. So when you reach out for yet another cookie or a bowl of ice cream at 10 pm, start asking yourself gently curious questions, why? Am I eating because it's a habit? Am I eating to numb some uncomfortable feelings? Is the craving comes because my brain is tired and wants to sleep, but I override it and continue watching Netflix? Am I eating to delay bedtime or procrastinate, like my 5-year-old, who wants to eat or drink right as he is ready for bed? 

So, to make smarter food choices, we need to talk about sleep. But ultimately, sleep has many, many benefits besides eating.

Mental health is impaired – as it relates to mood and memory. Immune function is compromised – increased rate of infection, tissue repair, etc. Gut health is impaired – decreased diversity and health of the microbiome. The gut immune system is impaired. 

Sleep also plays a significant role in regulating pain and many other symptoms of fibromyalgia, especially fatigue and brain fog. 

Most of the patients I see in my clinic have problems with sleep - either can't fall asleep, or staying asleep, or both, hypersomnia, or excessive sleepiness, and also have sleep disorders, such as sleep apnea or insomnia. Poor sleep and or a sleep disorder is actually a risk factor of developing fibro, implicated in triggering fibro flares, and a major contributor to the disability. 

So this is why I am spending so much time going over the health Trinity – Nutrition, Sleep, Exercise - the foundation of health. All of them will plan a significant role in your recovery. 

But sleep is special.  

Physical and mental impairment caused by one night of poor sleep is more significant than an equivalent absence of food or exercise. This is true. We don't feel super bad after eating one unhealthy meal or skipping one day of exercise, but just one night of poor sleep or sleeping out your normal routine can disrupt your life and feeling of well-being for days after. 

Emerging science shows that sleep is the most effective thing we can do to reset our brain and body health each day. 

 SLEEP IS NOT THE OPPOSITE OF WAKEFULNESS. Sleep is an essential physiologic state that is required for health and longevity. Some body functions only occur when you sleep. Sleep is an essential physiologic state that is required for health and longevity. Some body functions only occur when you sleep.

So how much sleep do you need? It depends on your age. 

Infants (ages 0-3 months) need 14-17 hours a day. • Infants (ages 4-11 months) need 12-15 hours a day • Toddlers (ages 1-2 years) need about 11-14 hours a day. • Preschool children (ages 3-5) need 10-13 hours a day. • School-age children (ages 6-13) need 9-11 hours a day. • Teenagers (ages 14-17) need about 8-10 hours each day. • Most adults need 7-9 hours, although some people may need less or more 6-10. • Older adults (ages 65 and older) need 7-8 hours of sleep each day. • Women in the first three months of pregnancy often need several more hours of sleep than usual. 

So what makes us sleep? What influences our sleep and creates the sleep-wake cycle? Sleep is actually more complicated than passing out of exhaustion at the end of the day. If you have ever raised a baby, you know how fragile the sleep system is and how babies have an internal clock regulating their time to sleep, eat and play. Oh boy, if that rhythm is screwed up, a baby may reverse the days and nights or become inconsolable at bedtime, and no rocking will put her to sleep. 

So we have two things that influence your sleep – when you want to sleep and when to wake up: 1) circadian rhythm -physical, mental, and behavioral changes that follow a 24-hour cycle. 2) sleep pressure – pressure for sleep (homeostatic sleep drive) that builds up in the body as the awake time increases. The pressure gets stronger the longer we stay awake and decreases during sleep, reaching a low after a full night of good-quality sleep. It is accomplished via a chemical called adenosine. So, sleep pressure arises from the accumulation of adenosine in the brain. 

Let's talk more about the Circadian rhythm; most of us heard about it and the hormone melatonin that plays a major role in keeping the circadian rhythm going. 

Circadian rhythm -physical, mental, and behavioral changes that follow a 24-hour cycle. There are actually numerous peripheral circadian clocks throughout the human body that drive circadian rhythms. A master circadian pacemaker (also called the circadian clock) in the brain's hypothalamus synchronizes and controls the timing of these peripheral circadian clocks, so they work together. The body's sleep hormone,  melatonin, and stress hormone cortisol levels typically follow a regular, 24- hour circadian rhythm or pattern. Melatonin eases you into sleep—and helps you stay asleep—while cortisol helps get you up and keep you awake. 

Circadian rhythms promote sleepiness before usual bedtime, help initiate sleep, and begin promoting wakefulness before the usual wake-up time in the morning. They also regulate many physiological and behavioral processes related to hormones, body core temperature, eating and digesting food, production of urine,  and mood and emotions. 

Circadian rhythms – prepare your body to expect when to wake up, be active, eat, sleep – internal alarm system. Circadian rhythms – get orientation from the light/dark cycle,  artificial light,  repeating activities at the same time - eating, temp, exercise, social activities at the same time. But daylight is the strongest and most reliable signal your brain uses to reset the clock. Circadian rhythm synchronizes activities sleep, feeding, and temperatures around Sun/Earth. 

So, wakefulness and sleep are under the control of the circadian rhythm – not the other way around. The circadian rhythm will not change if you did not sleep, but it can be shifted by having regular schedule and exposure to light. But everyone's circadian rhythm is not the same. "Morning" larks – about 40% - wake up around dawn and function better in the morning. "Evening" – 30% - naturally prefer going to be late – "night owls."  "In between" -30% - slight preference for later, but not late. Circadian rhythm is determined by genetics and kept by practice. The circadian rhythm will continue to go through the cycles, even if we are awake - we see it in shift workers, working early shifts or late/night shifts, or when you are forcing yourself to stay up, watch TV or take the red-eye. 

The brain uses MELATONIN – a hormone, and chemical messenger, to communicate to other body organs signals of day/night. Darkness prompts the pineal gland to start producing melatonin, while light causes that production to stop. Melatonin rises after dusk, letting the body know "it's getting dark." Melatonin helps regulate the timing of when sleep occurs – it tells the body it's dark, but melatonin does not generate sleep. Melatonin signals the brain and other organs; it's time for bedtime routine and sleep/night functions. Melatonin peaks around 4 am; after it peaks, the amount of melatonin gradually decreases. It's undetectable by early to mid-morning. The absence of melatonin – signals that sleep time is over. The cortisol helps get you up and keep you awake. Once you've woken up, the cortisol surge continues for 30-45 minutes before returning to its baseline after an hour or so. Don't be fooled that you can just take melatonin at bedtime and have a good sleep; there is an intricate balance between the amount of the hormone and the timing of the release and decrease and other hormones and body processes. 

This rhythm is controlled by a small part of the brain, known as the circadian pacemaker, that is powerfully influenced by light exposure. When light enters the eye, it is sensed by a particular group of cells on the retina; then, it is carried to the brain and interpreted as information about the time of day. The brain then sends signals throughout the body to control organs and other systems in accordance with that time of day.

When exposed to only natural light, a person's circadian rhythm becomes closely synchronized with sunrise and sunset -staying awake during the day and sleeping when it's dark.

When exposed to only natural light, a person's circadian rhythm becomes closely synchronized with sunrise and sunset -staying awake during the day and sleeping when it's dark. 

So why is this important to wake up on time, open up your curtains, not spend all day in the dark watching TV, taking a walk, or just sit outside, exposing your eye's retina to sunlight. But also, the exposure to artificial light at the wrong time messes up the sleep schedule by affecting the circadian rhythm. There is a health and hormonal consequences when you override your biology and continue watching TV, surfing social media on your phone, or playing a computer game after sunset, when the body is regulated by your hormones to wind down and sleep. 

So if you want to promote better sleep, wake up early, get light exposure, avoid electronics past 8 pm, or about 2 hours before sleep, avoid bright lights before bedtime in general, and have a routine, same schedule of waking up and going to sleep, meals, etc.. These routines will regulate the circadian pacemaker and help your body reset. 

Now let's talk about 2nd system we have that regulates sleep, the sleep pressure – pressure for sleep or the homeostatic sleep drive that builds up in the body as the awake time increases. The pressure gets stronger the longer we stay awake and decreases during sleep, reaching a low after a full night of good-quality sleep. Think of it as a pressure cooker - the longer it's on, the higher the pressure, and once it reaches a critical point, you feel the strong urge to sleep. The urge, just like the circadian rhythm, can be overridden by your thoughts, the brain cortex, up to a point. The override helps us stay awake when there is a need, like an emergency, or when you need to catch a flight up to a point. I remember staying up for my 36-hour shift in residency, functioning, but that was not easy. We all experienced a very strong urge to sleep, like put me down now, or I'll bust,  but we probably don't experience it that often. 

So the brain builds up this pressure from the moment you awake, which is accomplished via a chemical called adenosine. Sleep pressure arises from the accumulation of adenosine in the brain – every moment you are awake, the more adenosine you accumulate. High amounts of adenosine – turn up sleep areas of the brain and turn down activity areas of the sleep. When adenosine peaks – you get an irresistible urge to sleep, usually 12-16 hours past awake time. 

Well, when we can't override the sleep pressure by our conscious thoughts, we can reduce it by consuming caffeine. 

Caffeine is an adenosine blocker; it blocks the exact chemical that builds up in the brain as you stay awake. Caffeine – a psychoactive stimulant, it attaches to the same receptors in the brain as adenosine but does not stimulate the brain and does not make you sleepy. Caffeine tricks you into feeling more alert, temporarily. Adenosine keeps accumulating, even though it can not reach receptors blocked by caffeine. The peak of caffeine - is 30 min, but the half-life (50% of caffeine still present in the body) – is 5-7 hours. Cup of coffee – 7:30 - + 5 hours -> 12:30 50% of coffee is still active. Once the caffeine "falls off" receptor – you feel the effect of the accumulated adenosine – blocked and produced.

Remember Caffeine is not just in coffee. Many foods contain caffeine in various amounts, from chocolate, and energy drinks, to chocolate milk you may drink before bedtime. 

Circadian rhythm and sleep pressure system are separate and distinct systems that do not influence each other but are aligned. Both hormones- melatonin, cortisol, and adenosine/sleep pressure- coordinate wakefulness and sleep. So, if you are not having a regular sleep schedule and rely on caffeine to stay awake and don't ever see sunlight - guess what? Both systems are dysregulated and need to be adjusted separately. So, drink coffee about 12 you before you plan to go to sleep, get plenty of sunlight in your eyes, and keep a regular sleep schedule!

But guess what? There is another part of sleep regulation, and it's sleep cycles. The 90 min increments we actually sleep at night - the non-REM sleep and the REM sleep. 5 stages of the actual sleep- the awake phase, falling asleep phase, light sleep, deep sleep, and REM sleep. 

They all serve a purpose and need to be up and running properly for you to have proper quality sleep. 

During non-REM stages, your body: Builds bone and muscle. Repairs and regenerates tissues. Strengthens the immune system. As you age, you get less non-REM sleep. Older adults get less deep sleep than younger people. REM sleep plays an important role in dreaming, memory, emotional processing, and healthy brain development. 

Non-REM sleep: Falling asleep, light sleep, deep sleep. 

Awake – 1 st cycle – you just went to be awake. During other cycles, you will shift or wake up enough to get up/bathroom. It takes about 5-10 minutes to fall asleep. Everything starts to slow down, including your eye movement and muscle activity. Your eyes stay closed. If you get woken from stage 1 sleep, you may feel like you haven't slept.

Stage 2 is light sleep. 10-25 minutes, but the majority of the sleep cycle or  40-50 % are spent in light sleep. Your heart rate slows and, your body temperature drops, eye movement stops. Your body is getting ready for deep sleep. Periods of muscle tone (muscles partially contracting) mixed with periods of muscle relaxation. Brain waves become slower. Occasionally, you'll have a burst of rapid waves called sleep spindles. Stage 2 is important for memory, learning, and motor skills. Getting sufficient light sleep is essential to meeting your overall sleep needs.

Stage 3 is deep sleep. 45-90 minutes. up to 1/4 of your sleep time should be in deep sleep. It lasts for longer periods in the first half of the night and becomes shorter with each sleep cycle. You have no eye movement or muscle activity – "dead asleep." Muscle tone, pulse, and breathing rate decrease as the body relax even further. The brain activity during this period has an identifiable pattern of what is known as delta waves. It's hard for someone to wake you up during this stage. If you're woken up, you may feel groggy and disoriented for a few minutes. This is also the stage when sleepwalking, night terrors, and bedwetting occurs.

This is the stage when the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system. Deep sleep helps the brain create and store new memories and improves its ability to collect and recall information. This stage of sleep also helps the brain rest and recover from a day of thinking, allowing it to replenish energy in the form of glucose for the next day. 

REM - or Rapid Eye movement phase - 10-60 min, starts about 90 minutes after you fall asleep, and 1st REM period is short, about 10 minutes, but each cycle has longer REM periods. During REM sleep, there is an increased brain activity and muscle relaxation. Brain activity increases again, sleep is not as deep. The activity levels are like when you're awake. That's why REM sleep is the stage where you'll have intense dreams. At the same time, major muscles that you normally control (such as arms and legs) can't move. In effect, they become temporarily paralyzed.

Rapid eye movement - eyes move around rapidly in a range of directions but don't send any visual information to your brain. REM sleep plays an important role in dreaming, memory, emotional processing, and healthy brain function. 

So as you can tell, sleep is not only a very important part of your health, it is also a complicated one. The melatonin and circadian rhythm, the adenosine, and the sleep pressure, and the non-REM and REM stages of the sleep cycles, all play an important role, but can easily be dysregulated by the environment, medications or substances like caffeine, and most importantly, and probably most devastating, our free will, our ability to override this system and stay awake, past our scheduled and biological bedtime. 

Well, I hope this episode did not put you to sleep. 

As always, thank you for listening. and I will talk to you next week!