the importance of sleep + circadian rhythm
Getting enough sleep is vital for the body’s overall health and function. It is when our mind and body do the most detoxification and repair. Adequate amounts of sleep allow our body to support optimal brain function and maintain physical health. There are four stages of sleep — each one has a unique and specific purpose.
Our sleep/wake cycle is part of our body’s circadian rhythm (24-hour internal clock). The levels of several vital hormones within our body fluctuate in accordance with this circadian rhythm. Sleep and circadian rhythmicity are crucial for hormone balance and overall health. Sleep disturbances can negatively impact hormonal rhythms, metabolism, and so much more.
Keep reading to learn more about sleep, why we need it, stages of sleep, circadian rhythm and hormone production, and tips for the best sleep ever!
It’s an epidemic…
Seven hours (for adults) and nine hours (for teenagers) of sleep per day is the bare minimum amount of sleep needed for an optimized mind and body. According to 2023 data from the Sleep Foundation, around 33.3% of adults get less than seven hours of sleep every day; 58% of middle schoolers and 72% of high schoolers get below the minimum amount of sleep each day!!
Why is sleep important?
Sleep deprivation leads to the inability to function optimally, both mentally and physically. When you sleep, the brain and body emotionally and physically regenerate. If you are getting inadequate amounts of sleep, your body and brain are functioning at lower levels than normal. Over time, inadequate amounts of sleep can raise the risk of chronic (long-term) health concerns.
Sleep impacts:
growth and development
the repair of the body
detoxification
cognitive function - the brain!! (cognitive impairments and cognitive disorders)
your heart and circulatory system (cardiovascular health)
blood sugar (glucose) regulation - how your body responds to insulin
the immune system - affects your body’s ability to fight germs and sickness
hormone production and balance
the circadian rhythm - the body's intrinsic internal clock!
appetite - the hormone production of ghrelin and leptin
blood pressure regulation
metabolic function
respiratory system health
Understanding the stages of sleep
Getting a full night of sleep is crucial - understanding the process behind sleep helps us to understand why it is important to be getting adequate amounts of it. When we are not sleeping enough or getting low-quality sleep, our body is unable to experience all of the vital stages of sleep.
There are two main phases the body goes through while sleeping:
non-rapid eye movement (NREM)
NREM is divided into three stages: N1, N2, and N3
Around 75% of sleep is spent in NREM stages
rapid eye movement (REM)
Each phase and stage of sleep is unique, including variations in brain wave patterns and eye movements. These phases and stages of sleep make up a sleep cycle. A sleep cycle follows this pattern:
N1, N2, N3, N2, REM
We need four to six sleep cycles every 24 hours to function optimally. A complete sleep cycle takes roughly 90 to 110 minutes.
N1 (Stage 1) - Light Sleep (5%) - this happens when a person first falls asleep. The body and brain activities start to slow
N2 (Stage 2) - Deeper Sleep (45%) - the body enters a more subdued state, including a drop in temperature, slowed breathing and heart rate, and relaxed muscles
N3 (Stage 3) - Deepest Non-REM Sleep (25%) - this is when the body repairs and regrows tissues, builds bone and muscle and strengthens the immune system. This time is crucial for cognitive function as the brain creates new neural pathways, stores memory, etc.
REM (25%) - during this stage, brain activity picks up. REM supports emotional processes and helps us to regulate the emotional events that we encounter during daily life. This is when dreaming and nightmares occur. It is essential to cognitive functions such as learning, memory, and creativity
Circadian rhythm and hormone production
Circadian rhythms - evolutionary internal clocks
Circadian clocks are our bodies’ evolutionary internal clocks — a circadian rhythm is a periodic pattern that takes about 24 hours, where the light–dark cycles synchronize biological functions with the surrounding environment. The circadian rhythms within our body harmonize physiology and behaviors towards the environment, acting as our body’s intrinsic clock.
For example, when in sync with the environment, this clock induces sleep and other related anabolic functions at night, such as growth and repair, hormone production and regulation, immune function, and wakefulness. During the day, a synchronized circadian rhythm is associated with catabolic functions such as cortisol production, digestion, and physical activity.
Getting enough quality sleep at night is vital for the production and regulation of your body’s hormones. Sleep and its intrinsic circadian rhythm control the production, regulation, and metabolism of several crucial hormones. The circadian rhythm is largely intertwined with the production of rhythmic hormones such as melatonin, cortisol, leptin, ghrelin, insulin, and growth hormone.
melatonin - commonly known as the “sleep hormone.” This hormone is released by the pineal gland into the bloodstream. The production of melatonin is prompted by darkness. Light (sunlight, blue light, etc.) causes its production to cease. Melatonin initiates the inactive phase and increases the drive to sleep. As you can see, our bodies’ natural melatonin production is crucial to regulating the circadian rhythm (synching our body’s sleep and wake cycle with night and day)
cortisol - cortisol is largely known as our “stress hormone.” It is produced by the adrenal cortex. Rising cortisol in the morning hours initiates the active phase and readies us for activity. Cortisol levels should decrease throughout the day
Cortisol and melatonin have opposing rhythms. Regarding circadian timing, cortisol and melatonin are the primary chemical mediators that provide the signals that reset and harmonize our inner clocks. Ideally, when we wake up, we are exposed to the sunshine, which signals our primitive body to produce cortisol because we are starting a new day and need to be awake and ready. As the day goes on, our cortisol levels should decrease. Then, as the evening comes, the sun goes down, and we are exposed to less and less light, which signals our body to begin producing melatonin and readying for sleep.
This is the optimal and natural circadian rhythm in response to light and dark. However, there are many things in today’s world that can hinder our natural circadian rhythm and hormone production, such as exposure to blue light (phones, TV, computer screens, etc.) late at night!
leptin - leptin is a hormone produced by our adipose tissue (body fat). It is commonly known as the “fullness” or “satiety” hormone. Leptin sends a signal to your brain that helps you feel full and less interested in food. Leptin also plays a key role in the regulation of body fat. When we sleep, leptin levels should rise, subduing the need to eat by signaling to the brain that energy reserves are adequate for the time
ghrelin - ghrelin is a hormone our stomach produces and releases. It is sometimes referred to as our “hunger hormone” because it tells our brain when our stomach is empty and we need to eat. Ghrelin also helps trigger your pituitary gland to release growth hormone and plays a role in controlling sugars and how your body releases insulin, the hormone responsible for processing sugar
insulin - Insulin is an essential hormone produced by the pancreas that helps your body turn food into energy and controls your blood sugar levels. If you have diabetes, your body can’t make enough insulin or can’t use it properly
You may be wondering, what do sleeping and circadian rhythmicity have to do with hunger, fullness, and metabolism?! Well, everything! Daily appetite is a circadian rhythm and is intertwined with our sleep cycle. Ideally, in the evening, around dinner time, our ghrelin levels increase, signaling our body to eat a good meal in preparation for an overnight fast. Then, as we sleep, our leptin levels should increase, signaling to the brain that energy reserves are adequate and subduing the need for food.
However, sleep deprivation increases ghrelin levels while at the same time lowering leptin levels in the blood. This is because, due to the body’s energy depletion (from lack of sleep), the brain receives a signal of limited energy supply. Subsequently, the message sent out to the gastrointestinal tract is one of hunger, even though you may have eaten plenty of food.
Additionally, poor sleep decreases insulin sensitivity (increased insulin resistance), which means the body’s cells stop responding correctly to insulin, and blood sugar increases. Chronic sleep deficiency can cause severe diseases and conditions, including type 2 diabetes.
growth hormone - human growth hormone (HGH) or just growth hormone (GH) is produced while we sleep and is vital in maintaining metabolism, immunity, muscle development, and the production of proteins in your body. Not getting enough sleep limits the body’s ability to repair itself and recover from injury. GH also affects how your body metabolizes glucose. GH deficiencies can result in insulin resistance, increased blood sugar, dyslipidemia, and hyperglycemia, which contributes to an increased risk of cardiovascular morbidity and mortality
Overall, sleep habits impact EVERYTHING!!!! Sleep disturbances, which negatively impact hormonal rhythms and metabolism, are associated with insulin insensitivity, weakened immune system, obesity, diabetes, hormonal imbalance, stunted growth, the inability to repair muscles and tissues, appetite dysregulation, cognitive impairments, cognitive disorders, heart problems, etc.
Adequate sleep is crucial for harmonizing and balancing the body’s natural circadian rhythms and optimizing whole-body health. Here are some tips for getting a vital night's rest.
Tangible tips for better sleep!
reduce screen and light exposure - this is especially important 1-2 hours before bed!! Blue light disrupts the body’s natural circadian rhythm and production of melatonin! I recommend opting for dim lights and no screens at night!
sunshine exposure in the morning - Exposure to the sun’s rays in the morning helps to balance the body’s circadian rhythm and daily cyclical hormone production.
create a relaxing bedtime routine - have a screen-free and low-light bedtime routine! Try a nice bath, meditation, some tea, reading a book, self-care, a warm shower, etc.
eat a well-balanced dinner 2-3 hours before bed - circadian rhythms influence when we eat, and when we eat may alter our circadian rhythms! Eating a large meal right before bed affects our digestion and sleep quality. Digesting a large meal takes energy; this can disturb the body’s ability to wind down and go to sleep while also creating digestive discomfort. However, that is not to say you cannot have anything to eat 2-3 hours before bed — a small balanced snack before bed can be beneficial for blood sugar regulation and sleep quality!
limit caffeine consumption throughout the day - caffeine has a half-life of 6 hours, so for the best quality of sleep, drink caffeine before 10 a.m. Additionally, don’t drink caffeine on an empty stomach, as it will cause increases in cortisol. Caffeine AFTER breakfast and before 10 am will support blood glucose levels, energy, and mood throughout the day and promote sleep come night.
sleep schedule - go to bed at the same time most nights and wake up at the same time most days — this will help regulate and synchronize the body’s natural circadian rhythm! Getting to sleep before 10 p.m. and sleeping for 8-9 hours is optimal! For women, sleep requirements may shift throughout their menstrual cycle, which is normal (listen to and honor your bio-individuality and needs)!
try some herbal tea - herbal teas are caffeine-free and can help the body relax before bedtime. Herbs such as valerian, chamomile, lavender, skullcap, passion flower, lemon balm, peppermint, ashwagandha, and catnip are excellent sleep supporters! Look for organic herbal teas containing these herbs to sip before bed! My favorite bedtime teas are Nighty Night Tea and Cup of Calm by Traditional Medicinals
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