1. Every wonder why we use blankets to sleep?
2. Quick overview of how the hormones of sleep and metabolism are yoked.
3. See how several levees of the quilt are tied together.
4. Why the brain really needs to be understood for optimal health.
Today is a quick hitter post for those who are trying to regain leptin sensitivity. I have gotten many PM’s on Facebookand a ton of requests via twitter (@DigiSurg) and by email to post a synthesis post on how several levees tie together for metabolism and sleep. I would strongly recommend that you re read the first leptin and sleep blog to review some of the material as a nice primer.
Ok, so off we go.
1. Body temperature is controlled by the hypothalamus in the brain…and it also controls leptin status and sensitivity centrally via the hypocretin neurons (HCN). The HCN also help modulate our sleep by keeping the stages in order and working optimally.
2. So you ever wonder why we “like” to wear blankets when we sleep? Well, the reason is simple. Melatonin is made from our brain’s pineal gland from stored serotonin after four continuous hours of total darkness (the reason you need to avoid light after sunset). One of melatonin’s functions during sleep is to lower our body temperature. Why do you guess the brain would want to do this when we sleep you ask?
3. After the 4 hours of darkness, melatonin secretion increases and this allows plasma leptin to enter the hypothalamus if we are sensitive to its receptor. If we are resistant, this process can no longer occur. Once leptin enters and binds to its receptors, it affects the lateral hypothalamic tracts to immediately send a second messenger signal to the thyroid to signal it to upregulate thyroid function and efficiency. This specifically is how we can raise our basal metabolic rate when we are leptin sensitive. These coupled events, matched with leptin’s actions peripherally in muscles, occur at the UCP3 sites to burn fat as we sleep at a higher basal metabolic rate. This means electron chain transport does not make ATP as usual. When leptin allows this uncoupling to occur, we make heat and not energy from normal metabolism. This means we will burn off our excess calories as pure heat. This is one reason why calories in and calories out argument makes no biologic sense once you understand how leptin works. Humans are built to burn fat at night as we sleep to loose excess weight we don’t need. The timing of the leptin action is also critical. It usually occurs between 12-2 AM and is tied to when you last ate and how much darkness your eyes have seen. This generally occurs soon after our hypothalamus releases another hormone called prolactin from our pituitary gland in the brain. The prolactin surge does not happen if the patient has sleep apnea or ate some carbs to close to bedtime. If you eat any carbs and protein within 4 hours of sleep you will never see the prolactin surge because any spike in insulin turns off this critical release. Ok, you must be asking why is this prolactin hormone so important? Is not prolactin just a hormone to secrete human milk, doc? That is not the only action of prolactin. Immediately after prolactin is released at this time, another signal is sent to the anterior pituitary to release Growth Hormone (GH). GH is stimulated only during autophagic sleep cycles in stage 3 and 4 to increase protein synthesis for muscle growth all while you’re dissipating heat. This is the major release of GH in humans post puberty. The implications here are huge. If you are LR and have sleep apnea you will have an altered body composition because of a low GH level. It means as you age you have higher body fat and lower muscle mass. This is precisely what we see in humans as they age and invariably their sleep is also poor.
The reduced temperature induced by melatonin in sleep is needed for Central Nervous System autophagic repair for another less well known reason. The lowered temperature sets the stage for the biologic quantum effects to be optimal on neuron microtubules that facilitate learning and neuronal spouting that occur brain wide. This is why if you don’t sleep well you feel badly and your performance suffers the next few days on tasks. Research also shows your learning is severely impaired. This is why we monitor truck drivers and airline pilots sleep and wake cycles by law! Moreover, in hospitalized patients or the elderly when this occurs, it sets the stage for the appearance of acute onset delirium. We see this often in hospitalized patients who can not sleep well in ICU’s. Acute delirium states very much look the same as chronic sleep deprivation patients we see clinically as well.
4. Simultaneously, while sleep is rebuilding our cellular terroir (think levee one), the immune system is also undergoing autophagic repair…that is another reason why the temperature has to fall. Usually, temperature rises causes immune function to increase in response and duration in fever, stress and infections. This turning on depletes our immune system of its reserves. Dropping our temperature as we sleep allows us to repair it. During sleep this is when the body retools our immunity to function optimally the next day. What controls this entire orchestra of hormonal regulation? Its all leptin mediated…and the brain is the master receptive organ to its function.
That is why brain surgery is cool. Its my experimental lab and helps explain why disordered sleep and metabolism are coupled at multiple levels in the human.
Edited by missyo67 - Jan 31 2013 at 4:23pm