I still don't understand the significance of the prolactin surge (especially in older people).. what happens if you eat carbs within 4 hours of going to sleep? What is LR? I am neither a neurosurgeon, nor a scientist, nor a physician – is there any way to explain it in less technical terms.. thank you very much.
its huge......first step is Leptin levels rise slowly for fours post dinner. At midnight leptin then enters the hypothalamus. Once it binds to the receptor two things occur. The first is a second messenger is sent to the thyroid to up regulate T3 production to stimulate Uncoupling protein 3 in muscles to burn fat liberated as we sleep at a higher metabolic rate. These fats are burned not as energy but as free heat. It requires Leptin sensitivity and proper thyroid function at the muscle level.
The second effect is via another second messenger......the coupled receptor with leptin bound sends a message to the anterior pituitary to release prolactin from 12-2 AM......the prolactin release is required for proper control of sleep stages and yoking sleep and metabolism.....but the real benefit is this is the signal the hypothalamus uses to release puslitile Growth Hormone release from 2 AM to 5 AM during sleep stages 2-4. This allows the process of AUTOPHAGY to be of maximal efficiency as we sleep.
Recall that autophagy is the process of cellualr renewal. When we recycle proteins, learn, and retool our brains from yesterdays oxidative damage.
People who have sleep apnea.....are generally obese, Leptin resistant and never get their pulsatile GH release and as a result autophagy is poor in them......they suffer more diseases and age faster because their sleep is uncoupled from their metabolism.
Moreover they can never burn their excess calories as pure heat because the initial message was blocked........so they remain fat. They cant lose the weight either until they become leptin sensitive. When they do they notice a tremendous change in sleep........sleep is designed to be resotrative.
Prolactin is the trigger for GH release. GH decreases abdominal fat and increase your lean muscle mass and allows for major protein synthesis. Its levels fall off a cliff for most women after age 40 and for men after age fifty and there is a corresponding drop in the efficiency of sleep and autophagy. This is why older people sleep less than younger people. It is also why babies sleep so long.......this is when their GH is being released when everything is working optimally.
I hope this helps.
Forgot this one fact.......the more carbs you eat the more likely you will blow your prolactin surge. IE you will lose it. Prolactin is tied to carb intake by the actions of NPY. People who are leptin resistant have high levels of NPY. For prolactin to work best you need lower levels of NPY in the hypothalamus. So a reasonable carb intake must be done.
Reasonable depends upon the context. If you are very fit and ripped you can handle a higher carb load and still maintain low NPY levels.
Most americans cant do this because of the SAD. The chronic over eating of carbs has completely trashed their HPA axis so they need to eat a VLC paleo diet to get it all working correctly.
Regarding the prolactin surge and sleep EEG's...... around 90 minutes into the sleep cycle, dramatic events occur at the hypocretin neurons with the secretion of Prolactin. In terms of large-scale oscillations-and the large, slow waves over the entire brain are not going to be found. What we find are high-frequency, small-amplitude activity prevails, with greatly reduced correlation to normal sleep cycles. This phase is referred to as the "desynchronized state." In this phase, our eyes move rapidly back and forth and called "rapid eye movement" (REM) sleep. Most of our dreams happen during REM sleep and GH secretion is there too. 25% of sleep is spent in REM in healthy humans. Sleep apnea folks never get a wink of it. However, REM sleep occurs over approximately four or five cycles throughout the night, with each cycle being slightly longer than the previous one. Slow wave oscillation and memory consolidation happens in REM and this is where things are burned into our memories.
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