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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 my Dr. Jack Kruse Facebook page and a ton of requests via twitter (@DrJackKruse) 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?  The key protein however is something called melanopsin.  Melanopsin is the dimmer switch for the eye as light drops to darkness and works with the sun’s photoelectric effect.  When I get to quantum sleep you will see just how sleep is induced and how wakefulness was evolved.

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. Energy added to the system changes how the biochemistry actually works.  This is a macroscopic quantum effect in sleep. 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.



  1. Resurgent says:

    .."If you eat carbs within 4 hours of sleep you will never see the prolactin surge because any spike in insulin turns off this critical release…"

    So, almost NO ONE sees this prolactin surge? Eating carbs within 4 hours of sleep is the norm, across cultures and countries..!!

  2. In order to give your cell terroir the best environment for nocturnal repair, is there an optimum room temperature to sleep in? Should blankets be worn?

  3. @Resurg…….now you see why I am not a fan of late night carbs. Its OK for leangains to get ripped but not for longevity. Autophagy is how most hearts fail. And remember most people with severe sleep apnea die from heart failure. Think Reggie White. R heart failed and gave him pulmonary edema at 39 years old.

  4. @Tim…..Being leptin sensitive is far more important than ambient temp. But I will say this. You are more effective uncoupling if you sleep in very cold temps. You will also loose way more weight because on top of maximizing UCP3, you will also bring UCP1 function in to help you.

  5. Riveted says:

    Thermoregulation is a major issue in my life. About 2 nights a week I wake up in the middle of the night COMPLETELY drenched in sweat…like soaked. Is it external (too many blankets) or internal (hormones, carbs, evening glass of wine)?

  6. @ Riveted. Clear sign you have a hormonal imbalance. You need to eat the right fuel and do it using leptin principles. You will see an improvement but if its not marked then you need your other hormones checked and balanced with bioidenticals. Please let me know how you do going forward.

  7. Dr. Kruse,

    Don't bioidentical hormones downregulate natural hormones? Once bioidentical therapy is started, is there any going back?

  8. Now I know why I feel so rested when I am camping. We eat around sunset usually or before so we had light to cook by and then at night we are in total darkness and the temps would drop into the 60's. I guess I can tell my wife it is healthier to camp more. She will be so excited.

  9. @Bill…..we replace what we lose or have lost based upon testing. You dont take BHRT unless you need it.

  10. camping is pretty paleo as long as the food is.

  11. Adriana G says:

    "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"

    So…if you eat a low carb paleo dinner at 7 p.m. and go to sleep before 11 p.m. you block the prolactin surge?

  12. "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)."

    What does the 'it' in this sentence refer to? Does body temperature also control leptin status?

  13. "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."

    I'm confused by this sentence. I thought it was leptin receptors themselves that either are or are not sensitive to leptin. What does it mean to be sensitive to 'its receptor'?

  14. dr. k said: "You dont take BHRT unless you need it."

    the question is how do you know you need it to the extent that you will accept risks associated with it.

    you said you prescribed BHRT for bone loss. will your patient need to take BHRT indefinitely? i read that once HT is stopped, bone loss begins again.

    i took your advice and read ageless by suzanne somers. she had a reproductive cancer (uterus?) 9 years into BHRT. why are you confident that BHRT did not play a role in her reproductive cancer? also could you please cite the best study to date showing the benefits and risks of BHRT? thx

  15. @Adrianna…..yep. Eat earlier

  16. @ Taylor…..it just means we néed for leptin to be sensitive to it's receptor. No tricks here

  17. At V her cancer occurred nine years in…..and she is now twenty yrs into BHRT. That tell me she got Ca for what she was doing the forty years before she figured out to turn her switches off. The best studies of BHT are form europe because no one has sponsored a double blinded project of synthetics over bioidenticals. Why? Pharma does not want to lose money.

  18. Dr k are you saying a double blind trial of bioidenticals vs synthetics has been conducted in Europe? Could you please provide a citation to this study?

    Also, will the patient who you prescribed bhrt for boneloss need to continue taking it indefinitely? Thx

  19. Hey Jack!

    I've developed some sleep issues since I started the leptin reset about a month ago. I find it much harder to stay asleep 8 hours and I wake up earlier than I want to feeling hot and needing to pee. Then, once I get up, it's very hard to fall back asleep, but I'm tired and headachy. I'm waking up about 6-7 hours after falling asleep.

    I used to be able to turn over and fall back asleep if I woke early, but it's like my bladder feels more sensitive and I'm too hot. I'm not drinking water right before bed, either. This is really starting to mess with my energy levels:(

    Any ideas as to what could be going on?

    PS- I'm doing the reset mainly to help my hormone levels and shed a bit of stubborn belly fat (it's working for that!). I'm not overweight. I have a history of luteal phase defect/low progesterone and adrenal fatigue (which is not severe right now).

    I also have Hashimoto's, which I'm managing with an immune modulation protocol (it's helped me tremendously!) and I'm on dopamine support (again- really helpful!)

    On a more positive note, my cognitive function has really improved, even on days that I'm tired and I have almost no food cravings!

  20. Grammasmitty says:

    This is very interesting indeed! I've been hot all my life. My mother told me that even when I was a baby I always had a little swath of sweat across my nose and upper lip. It became VERY bothersome about my mid-40s and I would keep the house temp no higher than 65 year round. Nights were the worst, even before hot flashes began. I slept OK, but was always hot and couldn't cover up much.

    About 4 years ago I discovered hCG (Kevin Trudeau) and began losing weight. My heat disappeared! It came back every time I went off the diet/hCG (gained weight back, too). In March I learned about LR, tossed my hcg and began eating according to Byron Richards' guidelines. Not only was I losing (slowly) but the heat was gone. This past June I spent a month WAY off diet/schedule and it came back again. I've been following your advise for 2 weeks now. Heat is gone again, gained about 3#, but feel really good. Sleep is improving. But the big change I see is that my constant internal radiator has shut down!

    Reading this blog has pulled some of the pieces together for me. While on the hCG protocol, I was eating on a leptin diet schedule, mostly proteins, though very little fat, very few carbs at all. Makes sense. Am I concluding correctly?

    On a side note, When I was doing Richards plan, I ate 450-500 calories, protein/fat, very little carbs per meal, 3 times a day, NO snacking and was routinely losing 3 – 3.5# a week. Doing your plan, I stopped losing, then gained 3# and am holding steady. If I really stick to paleo and your guidelines, you can "promise" that I will do better on your plan than Richards' plan? And can you explain why this would be? What is the difference happening inside?

  21. Since you state GH released at night is the major secretion of GH in post-puberty teens, would this imply that a LR teen would face a stunt in height?

  22. I doubt I have ever in my life gone more than 2 days in a row not eating within 4hrs of bedtime, and I'm definitely (although wasn't until I was 30) overweight, sugar addicted, cortisol-upside-down, and all kinds of other screwed up, but … I've never had any trouble making enough milk, not once in 13 years of lactation.

    How does that work? Prolactin seems to be well off in my body, even if little else is.

    • @MomaGrok PRL has huge effects……i will cover that one soon. It is my secret weight loss weapon for post menopausal women.

  23. how to get healthy says:

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  24. CaptRover says:

    I'm a firefighter and I work, on average, ten days a month. I'm at work for 24hrs and my sleep can get interrupted multiple times through the night. I sleep very deeply and uninterruptedly on the nights I'm at home (especially now that I'm eating paleo and following the LeptinRx). I'm concerned about the effects of my current sleep patterns and was wondering if there is any way to make up for the nights of bad sleep?

    • @ Capt Rover Here is the good news and the bad. You can recover a sleep deficit in most cases. In fact it is more likely to occur if you are leptin Sensitive. I suffered from your exact problem when I was in residency. I am convinced what really got me to be a fat ass was poor sleep combined with a granola and vending machine diet while working 110 hour weeks for a decade. When I finished my residency at 12:30 PM on 5/31 after clipping a PCOM aneurysm (yes I remember the case like I just did it) I went home and was supposed to party like a rock star…….and I immediately slept for 18 hours. No kidding either. My conscious mine knew I needed to let it go…..and my brain said we need sleep. I think the Leptin Rx for you is critical…..why? The bad news is you can never be optimal if you constantly live incongruent to our circadian clocks. I found this out the hard way. it took me 8 yrs to correct it. Doctors and firemen are supposed to go all out time wise. Well this doctor no longer buys that line of BS. Take care of yourself because you are worthless to others if you are broken to yourself. This was the greatest lesson I learned from residency. I just wish I practiced what I preach now before 2007.

  25. CaptRover says:

    I am doing my best to avoid the chronic sleep deprivation that plagues so many of us. Please keep up the great blog. I am currently working to transform my life using your suggestions and can tell that I am already becoming more leptin sensitive. I have recently been tasked with helping a fellow firefighter turn his life around health-wise. This guy is in danger and labelled a "lost cause". He is morbidly obese with bad knees and back, along with metabolic syndrome and gout. I know I will face obstacles from management, the firefighter and other firefighters as I seek to implement a plan consisting of Paleo diet, Leptin Rx, and kettlebells (HIIT). I would love to seek your advice when needed and to update you as to my progress personally as well as my "patient"'s.

  26. Our body temperature falls while we sleep, but we're burning off excess calories as heat while we sleep – how do those two things relate to each other?

    Thanks for this post, very informative and will help me talk to my clients about sleep.

    • Fran calories burned do not always mean heat is released…..this does occor at UCP1 proteins but in the body most energy is conserved in the chemical bonds and the cofactors of the metabolic pathways. Total body heat is controlled by……you guessed the hypothalamus. The thyroid can modulate but can not control it. Endogenous Melatonin production from our pineal gland directly down regulates the hypothalamic body temp set point. Melatonin lowers it and infections raise it

  27. With DSPD and sleep apnea (tested obstructive apnea when obese, now just overweight.), sleep is difficult. Weight loss, side sleeping and sleep meds help. With the LR diet in the past few months, weight is stable, cravings gone, no snacking. First meal is at 1-2 PM, but because of weak LES and Gerd, I cannot eat more than 25 grams protein this first meal. Two meals per day. Third meal at night is just 6 oz. homemade Greek style yogurt and yes, 4 hours before sleep. My research finds that circadian rhythms can be tweaked but never changed. Do you agree? Been this way since childhood, and am now a senior. Is this an impossible situation? What can I do to make things better?

    • @PRJ I dont agree. I think we may not be able to change circadian cycles…..but we can tweek and adjust for them. I will give you a for example that you might consider yourself. When I see someone who has a big sleep problem I immediately want to know why…….and I dissect that with a long history. But when I want to fix it I go straight to a DHEA level to tell me degree of problem. Once I understand the cycle issue from the persons experience and see the brain's response we might then come up with a way to tweek the cycle. I really talk about this in the October 26, 2011 post on leptin. I think you might find that provocative for this problem.

  28. I have been plagued by insomnia for the past two years, the sort that hits four to five hours into my sleep. Usually never have trouble falling asleep initially. Rarely, I can manage to fall back asleep, but am exhausted the next morning. I'm trying to understand what's going on, given this blog entry. I'm 38, have dropped 20 pounds going grain free, with probably another 20 to go. I have only now discovered your blog and will be trying the no food before bedtime to see if it helps? Any other thoughts?

    • @Kate without testing no clue…….but I bet if you get a DHEA level it will be horrible. That is a constant finding with insomnia.

  29. What about people who can drop off to sleep quickly & easily (like falling off a cliff) and sleep soundly all night, no matter what they do with computers, TV, & lights?

    That's me…and I was borderline obese (about 1/2 of extra wt lost now). I sleep like the dead & only wake to go to the bathrm, and usually fall right back asleep. I used to feel TERRIBLE waking up from hubby's morning noise (7:30), but since starting the leptin reset 2-1/2 wks ago, I feel okay then, but still roll over & sleep until 10–like clockwork–and awake feeling really refreshed. Depending on bedtime, that's 9-11 hours of sleep!

    What could be going on here? And what time should we be going to bed, esp during the leptin reset?

    • @Mimidiet lots could be going on. My bet is that you may have an underlying sleep disorder youre not aware of. I have sseveral people who stalled badly and we could not figure it out and we sent them to sleep lab and boom…….sleep apnea and one had narcolepsy.

  30. I get it and I want to sleep. I am on the GAPS diet for one and a half years and for the last two weeks (since I started reading you Blog) am being careful to have my BAB and eat a light supper early. But still the insomnia that I have had for over 15 years continues. Are there steps that you could out line to correct the situation?

  31. I usually go to sleep at 10p. I almost always wake up between 2 and 3 am. I am insulin resistant and trying to correct that by

    adopting the Palio lifestyle.

    I am interested if you can explain my waking up at the same time every night.

    • @Roamer That is easy. You're leptin resistant at the liver level and no control over PEPCK. Go read Leptin part deux blog post for more info.

  32. Dan in Utah says:

    Sleep according to the bard,"Sleep that knits up the raveled sleave of care, the death of each day's life, sore labor's bath, balm of hurt minds, great nature's second course, chief nourisher in life's feast."

    Residency, then 6 years of every 3rd night call broke me down as well.

    Are there situations where sedatives or hypnotics are justified, or do they just muddy the waters?

    I imagine do you like to let diet and lifestyle changes get the sleep cycle back in balance. I know that my sleep has improved greatly since eating paleodiet, getting in my "cold therapy", and not eating late.

    Looking forward to the biochemistry of thermogenesis. :)

  33. Every time I eat liver, its like a sleeping pill or something, and its very fast. I struggle to stay awake at night, so I switched it to noon. Same deal. Do you think I should surrender to it or eat it later? Late food doesn't seem to disrupt my sleep. I used to always have peanut butter and apple before bed so I could sleep. (I found out I was allergic on GAPS)

  34. If I understand correctly brain temperature falls but muscle temperature increases while we sleep if the conditions you talked about are met. This jogged a memory of mine about one night in particular for me. I woke up feeling extremely hot around the back of the head, neck, and upper back. I felt the pillow I had been sleeping on and it was so hot I jerked my hand away in surprise. It reminded me of when I read about certain skilled Tibetan monks who could sit on the ground and melt away the snow in a circle around them by radiating body heat. I have never had this intense heat event happen to me again.


  1. [...] time to re read my previous leptin posts to give you a 30,00 foot view of leptin (1) (2) (3) (4) (5). This series is going to be laser like biochemistry on a 30 foot level. When we talk about this [...]

  2. [...] as well. Dr Kruse provides a quick and dirty break down of why sleep is importation in his blog: Sleep Ya Big Dummy  and he hits it again in Cold Thermogenesis 7 . I not only want to reverse PCOS, Insulin [...]

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