Sleep: Health’s Greatest Secret
There’s a reason we are always told to get rest before a big day. Sleeping impacts just about every system in our body. It sets a foundation for health.
How well we sleep is connected to our immune response, energy levels, cognitive function, physical performance, digestion, mood, you name it! Unfortunately, sleep and health seem to work cyclically - poor health cultivates poor sleep and vice versa.
While we sleep, the body works. Our cells regenerate, our tissues repair, we create memories and our hormones are sending signals to prepare the body for the next day. Keep reading to learn about how sleep affects each system of health.
Immunity
Sleep promotes immunity by helping to lower inflammation and producing more immune-regulating cells. Our immune system is made up of specific cells that target, fight, and "destroy” infections. While we sleep, our body upregulates our immune functions - producing protective immune cells. Poor sleep has been shown to decrease levels of protective immune cells like cytokines that are released while we rest to fight inflammation. Poor sleep also seems to hurt immune system memory. Just as we promote memory and learning while we sleep, our immune system increases its memory to use in the future while fighting disease.
The body releases and balances certain hormones while we sleep, and releases protective immune cells. Cortisol, our stress hormone, actually helps the body regulate its circadian rhythm (it’s sleep-and-wake cycle). Poor sleep disrupts and increases cortisol in the body. This increased stress creates low-grade inflammation. It creates a cycle in which poor sleep increases inflammation while decreasing necessary immune cells to help fight that inflammation. Below are just some of the many ways sleep impacts our health.
Heart Health
Sleep impacts heart health in many ways! Poor sleep is linked to increased blood pressure, increasing the risk of hypertension. Newer research has also suggested that poor sleep disrupts circulation and can lead to plaque buildup in the arteries, a known risk factor for stroke.
Brain Health
The effect that sleep has on the brain is something we can feel all day long after a bad night’s rest. That slow, sluggish feeling and brain fog stay with us throughout the day. Sleep not only makes us feel “off,” but it has physiological impacts on our brain health, cognitive function, and reaction time. Memories and learning are created while we sleep. Disrupting this process makes us more forgetful and can make it harder to hold on to necessary details and information.
Poor sleep also disrupts the aging process by making it difficult for cells to decrease inflammation and remove toxins or harmful proteins. Continuous poor sleep can eventually lead to cognitive decline later in life.
Digestion
Poor sleep has been shown to increase many gastrointestinal diseases such as GERD and IBS. Too little sleep seems to influence pro-inflammatory cytokines. This increased inflammation promotes stress on the body, which can lead to a myriad of health disruptions. When it comes to digestive health, it seems to also heavily impact our gut microbiome. Adequate sleep promotes gut flora diversity, particularly increasing amounts of some keystone bacterial species that help us thrive.
Lack of REM sleep also has been shown to impact our hunger hormones. Ever crave a lot of carbs after a late night out? Those are your hormones talking. Adequate sleep promotes appetite control and allows us to better absorb and break down food, so we can use our food as energy. Because of this, good sleep also helps us maintain a healthy weight.
Performance
It is no secret that a good night’s sleep leaves us feeling refreshed, energetic and more alert - qualities any athlete hopes to have while training. Aside from preparing the body for a more challenging workout, sleep has been shown to decrease the risk of both injury and illness in athletes. Sleeping greater than 8 hours has been shown to decrease sprinting time. Other studies have shown lack of sleep decreases motivation and reaction time, while also generating accumulating fatigue - meaning athletes were getting more tired throughout their workouts.
Mood
Have you ever felt “cranky?” If so, you are not alone. Lack of sleep leads to stress, and stress can cause all kinds of disruptions in our moods. When studied, poor sleep is linked to increases in depression and anxiety, as well as feelings of “negativity and irritability.” Unfortunately, the sleep-mood relationship is cyclical. Our mood can negatively impact our sleep, and poor sleep can negatively impact our mood. Breaking the cycle by creating a nighttime routine, limiting screen time, or allowing yourself to relax before bed can be a game-changer when it comes to supporting both your mental and physical health.
References:
https://www.thelancet.com/journals/langas/article/PIIS2468-1253(19)30412-1/fulltext
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4849511/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6779243/
https://journals.lww.com/acsm-csmr/fulltext/2017/11000/sleep_and_athletic_performance.11.aspx
https://www.gssiweb.org/sports-science-exchange/article/sse-167-sleep-and-athletes
https://aasm.org/extended-sleep-improves-the-athletic-performance-of-collegiate-basketball-players/