Sleep, something most of us wish we were doing instead of smelling a stranger’s arm pit on the tube. I touched on this topic in my earlier post but because I think the effects of having too little are interesting, I decided to write a separate blog post on it.
Firstly, none of us have lived under a rock (nor do, if you’re reading this) so we all know it’s important for us. We try and make our children abide to a bed time so they would feel energized for the next day. However, as adults we tend to put less emphasis on it. I am a typical example; I go to sleep way to late and certainly don’t get at least 7 hours of undisturbed sleep.
I won’t die from my dodgy sleep routine, but I also know I could be a bit slimmer, healthier, productive, creative and calm if my sleep was on point. This is because sleep has a great effect on the following hormones:
- Ghrelin- hunger hormone
- Leptin- satiety hormone
- Cortisol- stress hormone
- Melatonin- sleep and wakefulness hormone
- Growth Hormone- can you guess?
Let’s explore the way ghrelin and leptin concentrations are effected, as they do the opposite jobs, and thus, go hand in hand. A lack of sleep has been proven to increase ghrelin and decrease leptin concentrations during the night. Ghrelin levels should decrease during the second part of the night suggesting an inhibitory effect of sleep on the hormone. Consequently, leptin levels normally are elevated to inhibit hunger during the overnight fast. However, a prolonged wakefulness results in reported increases of hunger and appetite levels the next day. This could possibility be due to the need to replenish the extra calories they used up. In theory it would be okay, but the participants wanted to eat much more than the extra calories they used up.
Cortisol is next up under the microscope. Normally, it starts rising the moment you wake up and reaches maximum levels an hour after. Throughout the day it falls in concentration to have the lowest concentration at bedtime. Only 2-3 hours after the onset of sleep does Cortisol start to creep up again. The increase commences till the morning. But if you have had days of little sleep, the concentration of cortisol take 6 times longer to decrease before bedtime than in a person who has had the recommended 7-9 hours of sleep. This make it hard to relax and ease into sleep. Lastly, the hormone elevation leads to insulin resistance, decreased glucose tolerance, and can make you more prone to diabetes and obesity.
Growth hormone (GH) secretion is also altered by lack of sleep. GH is responsible for repair and restoration of the body. GH has several peaks during the day but the biggest is during the night. If a person is sleep deprived then GH concentration is lower than one who has the right amount of sleep. Repair and restoration is vital; we need to repair microscopic muscle tares, neural connections, skin lesions, headaches, acne and all the other things so the body feels strong the next day. So, you can see why we should aim to get a good hit of it.
Lastly, melatonin is the sleep regulating hormones and is obviously influenced by the lack of sleep. It is lowest during day, due to high light exposure and thus the inhibition of its production, and high at night when low levels of light are sensed. However, if we stay up and are exposed to light, melatonin will stay lower than it should be. A decreased concentration of melatonin in the blood results in a lack of free-radical clean up as melatonin is a potent anti-oxidant. A decreased level of melatonin can also contribute to a weaker immune system and increased signs of aging.
Altogether, the evidence points highlight how good quality sleep can help with weight loss, stress relief and overall body wellness and beautifulness. Moreover, a lot of clinically diagnoses conditions are due to an imbalance of hormones. This can be addressed through adopting a good sleep habit.
*Below are a few graphs that illustrate the way the hormones behave in relation to different sleep duration’s:
Graphs drawn up from a study that examined appetite regulation after 2 nights of 4 h in bed and after 2 nights of 10 h in bed, in a randomized cross-over design. This study confirmed the decrease in leptin levels seen in the previous study, with a 18% decrease of leptin levels after the short nights relative to the long nights. Furthermore, ghrelin was assayed and showed a 28% increase after the 2 nights of 4 h in bed. Questionnaires on hunger and appetite were completed and indicated a 24% increase in hunger and a 23% increase in global appetite after the 4-hour nights versus the 10-hour nights. Appetite for high carbohydrate nutrients was the most affected with a 32% increase. Importantly, the subjective report of increased hunger was correlated with the increase in ghrelin to leptin ratio (i.e. hunger factor/satiety factor). These observations suggest that in real life, when food is available everywhere and all the time, sleep deprived people may consume excessive amounts of calories, particularly from carbohydrates. A recent study tested this hypothesis using a randomized cross-over design with either extension or restriction of the usual bedtime period by 1.5 h for 2 weeks in the laboratory. The subjects were middle-aged over weighed individuals who were exposed to unlimited amounts of palatable food presented in 3 meals per day and snacks were continuously available. The volunteers consumed excessive amounts of calories from meals under both sleep conditions but consumed more calories from snacks when sleep was restricted rather than extended.
Graph showing the plasma concentration of melatonin in different age and sex groups.
Sorry guys, couldn’t find a graph that shows an altering ghrelin concentration but I did find this that illustrates the point I was trying to relay.
Lots of kisses,