Over this past summer I read a really interesting article in National Geographic that mentioned how our society has made "sleep deprivation a lifestyle", yet everything we learn about sleep suggests how important it is to both our physical and mental health (Finkel, 2018). In fact, I would argue that sleep is just as important as both nutrition and physical activity. When working with all my clients who want to lose weight I am always discussing sleep, activity, and nutrition, as they are all interconnected.
What makes sleep so important?
Keeps you energized
Improves productivity and concentration
Good sleep often translates to lesser calories
Sleep supports your immune function
Poor sleep leads to an increased risk of chronic disease (e.g., diabetes, heart disease, etc.)
Poor sleep can lead to weight gain or difficulty with loss
Poor sleep has been linked to increased inflammation
Before getting into the nitty gritty about sleep, hormones, and weight, I want to take a step back and talk about circadian rhythms.
What is a circadian rhythm?
In simplest terms it is a 24-hour clock running in the background of your brain and it cycles between sleepiness and alertness. For most adults (with regular schedules) the sleepiness is at it's ultimate peak between 2-4am (you might be in your deepest sleep at this time). We often find this sleepiness peak sometime in the late afternoon (between 1-3pm), which could explain why you reach for that afternoon coffee or sugary treat. Of course this sleep-wake cycle will vary based on your sleep routine and whether or not you're a night owl or morning person (National Sleep Foundation, 2018).
There are two extremely important things to note when it comes to your circadian rhythm
1) When you are sleep deprived, you will notice much bigger swings in your sleepiness and alertness. If you are sleeping enough your energy should stay relatively stable throughout the day.
2) Lighting effects your rhythm. When it's dark out, your eyes send signals to your brain telling your body it should be tired (this is why getting up in dark weather is so much more challenging). When it's dark your brain then signals the body to produce melatonin, which plays a role in making your body feel tired. So we know that light impacts your circadian rhythm, which means the use of our light shining devices (phones, tablets, TV) also impacts this rhythm.
So, what's the connection between sleep and weight?
Irregular sleep disrupts the circadian rhythm, which then disrupts the endocrine hormones. Specifically, cortisol and your appetite hormones (ghrelin and leptin).
Cortisol is a chronic stress hormone that naturally follows your circadian rhythm. This means it is highest when your basal metabolic rate is highest (for most people that's usually mid day) and lowest in the evening or as your body begins to wind down before bed. However, without enough sleep cortisol levels can stay elevated. This extended elevation can lead to restlessness, chronic stress, and memory or cognitive functioning issues. In addition, elevated cortisol has been linked to increased appetite. So, if you are someone who tends to stress eat, it might be related to an actual increase in appetite along with other emotional eating patterns.
Ghrelin hormone is produced by the gastric fundus (a part of your stomach) and stimulates appetite. This hormones appears to be higher in those without adequate sleep.
Leptin hormone is produced by the adipose tissues after eating to signal satiety or fullness. Research has found that those without adequate sleep have lower leptin levels.
Bottom line: without enough sleep your appetite and stress hormones are working against you!
So what does this all mean?
These changes in hormone levels due to lack of sleep have been associated with poor eating patterns, which in turn can lead to weight gain over time. Studies have found that short sleepers tend to eat more unhealthy items and less fruits and vegetables compared to those who more.
In general, short sleepers is defined as 6 hours or less per night. In fact, people who don’t get enough sleep eat twice as much fat and more than 300 extra calories the next day, compared with those who sleep for eight hours.
In addition, those with less adequate sleep tend to crave sugary and caffeinated foods throughout the day to help naturally boost energy. This becomes a vicious cycle as we eat sugar to increase alertness, which then causes a spike in the blood sugar and quick crash that leads to more fatigue. This cycle of spikes and crashes also makes it challenging to make time to be active, which further exacerbates the vicious cycle of fatigue.
Bottom line: We need more sleep. The general recommendation being 7-9 hours each night. Click here to see the National Sleep Foundations Guideline for each age group.
Sleep influences how your body works, from your appetite to your cognitive functioning.
Sleep influences your energy levels throughout the day, your food choices, and your ability to be active.
So, how do you change your routine and get more sleep? Stay tuned for my follow up blog next week to get some practical tips.
In the meantime, if you'd like to read more. Check out this national geographic article all about the science of sleep, it's an interesting read. Click here!
Until next time,
Eat Right Feel Right - Angela and Victoria XO
Berger, N. A. (2014). Impact of Sleep and Sleep Disturbances on Obesity and Cancer. London: Springer.
Maggio, M., Colizzi, E., Fisichella, A., Vallenti, G., & Ceresini, G. (2013). Stress hormones, sleep deprivation and cognition in older adults.
Song, H., Sun, X., Yang, T., Zhang, L., Yang, J., & Bai, J. (2015). Effects of sleep deprivation on serum cortisol level and mental health in servicemen. International Journal of Psychophysiology.
National Sleep Foundation (2018). Circadian Rhythm and your Body Clock. https://www.sleep.org/articles/circadian-rhythm-body-clock/
Michael Finkel (2018). While We Sleep, Our Mind Goes on an Amazing Journey. National Geographic. https://www.nationalgeographic.com/magazine/2018/08/science-of-sleep/?user.testname=photogallery:2