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I think a clear vision is severely underrated!
It's easy to overlook it and just go to hard work, intelligence, perseverance, etc. (which are definitely important) but without a clear vision or direction you can waste resources going in circles or banging your head against the wall.

Being able to remain conscious during all sleep stages is the ultimate skill. This will open doors to almost anything.
- Introduction
When people want to have a deep meditation, they either try to:
(A) lower their brainwaves, and thus make their consciousness more non-dual. This includes techniques like: Kriya yoga, trance, hypnosis and the majority of all meditation techniques. (B) directly make their consciousness more non-dual. This includes contemplation and self inquiry.  When people try to get into lower brainwaves, they usually start from their everyday waking consciousness. This works, but it will take ages (lifetimes for most people) till you get into really deep brainwaves - even if you do very direct techniques like trance.
We already spend 8 hours each day in very deep brainwaves. Why not take advantage of that? So rather than trying to bring lower brainwaves to waking cosnciousness (tirelessly trying to lower your brainwaves during the day), we can try to bring consciousness to lower brainwaves. 
That is sleep yoga.
 
- Benefits of Sleep Yoga
All of your dreams will be lucid (2 hours each night) During the rest of the night (light and deep sleep) you can either abide in deep non-dual awareness (by far deeper than any normal meditations), or astral project as much as you like. You gain 8 hours each day (~ 3 000 hours each year) No lapse of consciousness upon physical death.  
This is obviously very significant for enlightenment. Apart from that, it will benefit you in so many ways. Merely the 2 hours of lucid dreaming each night will radically transform your psyche. Here I wrote about reasons why to bother about OBEs: 
 
- Difficulty
Monks usually require many years of training till they are able to remain conscious during sleep. It takes long because their techniques are not Fire. They usually consist of standard meditation, waking up a couple of times during the night and visualization techniques.
I've lately done a lot of research and experimenting and tried to combine all the hacks and tricks I found. This should make the process a lot quicker.
Before I get to the technique, let's first lay a foundation. (or jump to "Chapter 2: The Technique")
 
Chapter 1 : Sleep - 1. Basics
During the night you go through several sleep cycles, each around 90 minutes long. Sleep cycles consists of:
- N1( light sleep). Only when falling asleep.
- N2 (light sleep):
Usually around 50-60% of your sleep. N2 is the ideal sleep stage to wake up from - N3 (deep sleep = SWS = slow wave sleep):
Important for regeneration Around 20-25 % of your sleep. You need typically 60-120 minutes of SWS. defined as having more than 20% of delta brain waves.  Majority of SWS during your first few sleep cycles - REM  (rapid eye movement) :
Here you have most of your dreams brainwaves somewhat similar to your waking state sleep paralysis so you don't act out your dreams 20-25% of your night  you need 60-90 min of REM As the night progresses, each sleep cycle contains more and more REM A sleep cycle usually begins with N2. Then N3 then N2 again and then REM.
 
- 2. Segmented Sleep
About polyphasic Sleep: https://www.polyphasic.net/introduction-to-polyphasic-sleep .
Segmented sleep means dividing your sleep into 2 segments: See https://www.polyphasic.net/schedules/biphasic/ and https://www.polyphasic.net/schedules/dual-core/ .
SWS peak is usually at 9-12 pm. And REM peak is at 6-9 am. Sleeping during these times means most efficient SWS and REM. More about that here: https://www.polyphasic.net/sleep-mechanics/biological-rhythms/ and here: https://www.polyphasic.net/blog/three-noons-and-their-importance-to-determining-the-shift-in-circadian-rhythms/
 
- 2.1 Benefits of segmented sleep:
Having a REM core with little or no SWS is perfect for trying to learn sleep yoga, more on that later You have a heightened likelihood for lucid dreaming during the REM core because of the high REM percentage and the long time awake after your SWS core. You basically have a very long WBTB (wake back to bed). The longer a WBTB, the more effective.  Prolactin surge benefits: https://www.mattressnerd.com/polyphasic-sleep/overviews/segmented-sleep/ If you sleep monophasically, you can't cover both SWS and REM peaks. Thus segmented sleep is more efficient. ... therefore you need less total amount of sleep Yogis say that the time at around 3-5 am is most valuable for meditation If you usually sleep 8 hours, you could schedule a 3 h SWS core and a 4.5 h REM core.
The time between the SWS and REM core should be at least 2 hours. Ideally 3-4 hours. Otherwise your body treats it as interrupted sleep rather than segmented sleep and you don't get all the benefits. More time between your cores also means that you cover more of the SWS and REM peak.
Segmented sleep is not something to do occasionally. You need to do it every night, otherwise you will just be tired and not get all the benefits. Your body needs 1-2 weeks to adapt to the schedule.
Segmented sleep is not necessary, but it can help a lot. Alternatively, you could just sleep for 4-6 hours and then either add a normal WBTB or just go straight to the techniques.
 
- 3. SWS Core
- 3.1 Binaural beats
If you listen to delta binaural beats, you increase the duration and depth (decrease the brainwave frequency even further) of your SWS. For example, in this study ( https://www.frontiersin.org/articles/10.3389/fnhum.2018.00387/full )   they played 3 Hz delta binaural beats when the subjects were in N2. Thus, some N2 turned into N3. The length of N3 increased by 30% (N3 length of first two nights without binaural beats was 93 min. On the next night, with binaurals, N3 was 126 min). The subjects were probably new to binaural beats. If you have already trained your brain with binaural beats, the effect could possibly be even more drastic.
Using a sleep tracking device might be helpful to keep track of your SWS.
I recommend you try the binaural beats from Jody Hatton. Either on youtube:   
or on his website. you decide the price for a download.
Sleeping with headphones might not be the most comfortable. But it can be worth it. Delta binaural beats are only interesting for your SWS core. Instead of over ear headphones, you could also use headband headphones like these: https://www.amazon.com/gp/product/B014T3QLBA/ref=as_li_tl?ie=UTF8&tag=9td9sm-5xsk-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B014T3QLBA&linkId=82c4b0488d4ece45af2f57a9ea6427c0. they are more comfortable to sleep with. But might have lower quality.
I don't recommend opting for isochronic tones for delta sleep. They do have the benefit of not neading headphones, but they are said to be inefficient to entrain you to delta brainwaves.
- 3.2 Melatonin
Melatonin is important for SWS. How to optimize Melatonin levels:
Only red lights 2-3 hours before bed (or no light). You can buy red light. Or wear blue light blocking glasses (preferably should block green light as well) or use apps on your mobile phone and pc (for example "Flux") which filter blue light. Sleep in total darkness. Either buy something to block all light from your windows or just take a huge sheet of black carton and tape it over your window. Thats what I do. It takes around 1 minute each morning and night to tape/remove. You could also use a sleep mask. But then, a small amount of light is still registered by your skin. But that is probably negligible. enough (sun)light during the day. decalcify your pineal gland fasting can increase melatonin levels as well. - 3.3 Schedule
For our sleep yoga practice, we prefer to have all our SWS during the SWS core. So the REM core can be fully dedicated to Sleep yoga practices.
If you want to get the most out of each night, you also want to have as little light sleep and REM during your SWS core. You want these in your REM core so your REM core is longer and you have more time to practice each night (First we learn to be conscious during light sleep and REM, and only then do we try it during SWS). Depending on your personal SWS needs (which can vary a lot) and depending on how well you can optimize a sleep cycle for maximum SWS, you can choose following SWS core lengths.
6h: easy 4.5h: Healthy and comfortable  3h: for serious practitioners 1.5h: not recommended  I think you don't need to strictly schedule according to the 90 min sleep cycle rythm. You can extend it if you want.
A very unrecommended polyphasic sleep schedule - Everyman 4 : https://www.polyphasic.net/schedules/everyman/  - has only one 90 minute SWS core plus 4 short naps for REM. Someone who follows that schedule tries to get all 90 minutes of SWS requirement into the 90 minute core, which is close to impossible. For our use, if you perfectly optimized it and extended the length from 90 to 100-110 minutes, you might be able to get 70-90 min SWS into a 110 min SWS core. But beware, if you shorten your SWS core too much, you risk SWS creeping in to your REM core.
 
- 4. Core Gap
Once your body adapted to the new schedule, you won't be as tired during it After spending some minutes on my mobile phone, I'm fully awake. Make sure your devices block blue light. And I use a red light. And I also listen to gamma binaural beats. I like these: https://www.brainwave3d.com/spiritualitaet/erleuchtung/38/the-gateway-to-enlightenment-das-tor-zur-erleuchtung?c=30 and  https://www.brainwave3d.com/meditation/tiefenmeditation-fuer-profis/96/god-consciousness-gott-erleben?c=30 and  https://www.brainwave3d.com/psi-faehigkeiten/dmt/98/mystical-dmt-trip-erlebe-eine-intensive-dmt-erfahrung?c=34 (Use google translate for the website.) The "core gap" is a good time for meditative practces, just make sure you don't fall asleep. If you are likely to fall asleep during meditation, then do it right at the beginning or end of the core gap. So you still have at least 2 hours of continued wakefulness. I recommend spending a few minutes of hard-core concentration at the end of your core gap, as a preparation for your REM core practice.  
- 5. REM Core
-5.1 Basics
Your REM core should ideally consist of only light sleep and REM. Consider:
Getting enough SWS during your SWS core Having your REM core during or close after the REM peak Applying tricks for lighter sleep You will set MANY alarms which wake you up all the time, giving you plenty of opportunitues and optimal conditions to practice.
 
- 5.2 Gamma brain waves
I believe they are the key for being conscious during sleep. Monks have increased gamma acrivity during non-REM sleep: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0073417#pone-0073417-g001 .  The significance of 40 Hz for lucid dreaming:  https://www.google.com/amp/s/www.zmescience.com/medicine/mind-and-brain/lucid-dreaming-electrical-trigger-042342/amp/ . I guess, the main difference of brainwaves during sleep, between a sleep yogi and a normal person, is gamma activity. The more gamma (and beta) you have, the more alert/aware you are. So if we want to be aware during sleep, we need more gamma during sleep.
How to have more gamma during sleep:
gamma brainwave entrainment audios during sleep.   Applying the tools for having"Lighter Sleep" (more on that later) day-time meditation practices (more on that later)  
- 5.3 Schedule
If you are concerned about your sleep, then do the practices only for 1-3h, and then turn off all alarms, go back to sleep and sleep as long as your body wants. Depending on how easily you tend to fall asleep on any given day, you spontaneuosly decide for the right amount of "lighter sleep" tools.  
- 6. Lighter Sleep
- 6.1 Benefits
You are closer to the awake/asleep threshold. That means a) it is easier to retain consciousness while falling asleep and b) it is easier to stay in that state. The deeper your sleep gets, the greater the risk of losing consciousness decreased risk of SWS creeping in increased likelihood for DILDs, WILDs and DEILDs better dream recall  - 6.2 How to have lighter sleep:
- 6.2.1 Body Position:
Level1: Turn in bed 180 degrees. So your head is now where your feet used to be. Level 2: lie on the floor.  Level 3: Be in an inclined position. for example of 60 degrees. https://www.theminimalists.com/drew/  Level 4: Sleep sitting upright with head support.  Level 5: Upright with no head support. That is particularly good, because everytime you fall asleep, your head drops and wakes you up. Thus it is easier to get closer to the awake/asleep threshold. - 6.2.2 Noise
Tv or music.  listen to a hypnosis audios about falling asleep.  
- 6.2.3 Gamma brainwave entrainment:
I listen to these binaural beats during my REM Core:   https://www.iawaketechnologies.com/product/gammaburst/ . You can cutt off the beginning and end so that it's only in the relevant frequency of 25-45 Hz. I listen them during my whole REM core. Another option are these 40 Hz isochronic tones: https://www.iawaketechnologies.com/product/gamma-40/ . But I only listened to them once, I found the binaural beats more effective. But they have the advantage of not needing headphones. - 6.2.3 Discomfort.
Level 1: wearing headphones Level 2: Add any discomfort you can think of Level 3: Hold your arm up vertically. Ellbow supported on the matress. https://www.dreamviews.com/attaining-lucidity/107214-wild-awareness-training.html - 6.2.4 Alarm clocks
Level 1: Every 15-30 min. It turns itself off. So you have a lower likelihood of waking up if you are in a somewhat deeper sleep.  Level 2: Every 8-12 min. Alarm needs to be manually turned off. (you press snooze. So it will ring in a few minutes again) Level 3: Every 3-8 min. Alarm needs to be manually turned off Some alarm clock apps are able to play the alarm through your headphones only.
- 6.2.5 Light: 
Level 1: Leave on some red light Level 2: Remove your curtains from the windows just before your REM core Level 3: Turn on artificial light. Light will have a negative impact on your melatonin levels. In terms of melatonin, we are most concerned about it's effects on SWS sleep. So light after your SWS sleep is relatively fine. It is recommended that one spends 8-10 hours in darkness (or at least red light rather than blue light) each day. So if you turn off normal lighting 3 h before your SWS core, then have a 3 h SWS core, followed by a 3 h core gap, you have 9h.
- 6.2.6 Others:
Intention  uncomfortable temperature   
 
Chapter 2: The Technique Our approach consists of:
SWS Core Core Gap REM Core + Alarm Clocks  and there you practice "Conscious Falling Asleep"  
- 1. Getting yourself closer to sleep
Some tips:
Reverse Blinking. Thats very effective to get tired very quickly. Close your eyes for 2-7 seconds, then open them briefly. Continue till you are very tired. https://www.dreamviews.com/attaining-lucidity/24607-inducing-trance-wild-part-1-a.html Hypnotic suggestions/affirmations "sleepy" Concentrate on the "sleepiness" sensation and deepen it Pretend having fallen asleep  
- 2. Awake/Asleep Threshold Tools
Everything I listed under "Lighter Sleep" can be helpful to remain conscious during the awake/asleep threshold. Particularly powerful is:
Holding up your arm vertically, ellbow resting on the mattress. Sleeping sitting without head support. When you fall asleep, your arm or head will sink/fall down and wake you up.
 
- 3. Deepen your Trance
When trying to fall asleep, you are basically in trance. When you deepen your trance, you get your body closer to sleep. But apart from that it also alters your consciousness in a different way (than just using normal tips like those listed under "getting yourself closer to sleep") which can be helpful for conscious falling asleep.
- Tips for deepening your trance:
Falling sensation. Either visualize how you are somewhere else - in a visualized body - and experience a falling sensation there (literally falling, going down steps, elevator, etc...) or 'stay' with your consciousness in your physical body and visualize the falling sensation there (I personally prefer that). Try to visualize the sensation you have in your gut when being on a roller coster.  
Use Hypnosis. Here I wrote in detail about hypnosis (keep in mind, when I wrote older posts, I had less understanding):   
Use your Hypnotic Triggers. You can anchor every state of consciousness. so for example anchor being sleepy with the word "sleepy", or anchor going into a deep trance with visualizing going downstairs. Hypnotic Triggers are like key words for your subconscious that tell it what state of consciousness to produce.  
Visualize it into being. Visualize how you are in a very deep trance. Visualize having no more body sensations and being in the void. It's hard to expplain how exactly to do it, but it works.  
Visualize how you are expanding. Expand your consciousness to include your room, then house, etc. It is said that this produces more theta brainwaves   
 
Fractionation: A hypnotic induction technique. The idea is to get out of trance and then immediately go back down. If done skillfully, you will end up deeper than where you started.  One way to do it is to count from 1 to 3 (feeling how you are getting more out of trance with every number), open your eyes, count down from 3 to 1 (feeling how you are getting deeper), and closing your eyes again.  
Dissociation from the body. Some possibilities: Pretend that you are lying in bed upside down. Your head where  your feet used to be. Till you are actually convinced. The axis going from your feet to your head. Visualize turning around that axis. Like you are rolling in bed.  Visualize how you are in a visualized body in your room. Turn around and look at your physical body  
Try to induce the sensations of your body: becoming heavy.  quickly shrinking, expanding, shrinking, expanding, .... feeling strange  becoming weightless having no sensations melting with the room fading out of existence  
Completely surrender. And use some of your non-dual hypnotic triggers  
Visualize how you are in a visualized body somewhere. For example in your kitchen. Try to immerse yourself in these visualizations as much as possible. This produces deep theta brainwaves. And the more often you change your environment (particularly using doors, floors, etc) the more theta brainwaves are produced. So they say at least.  
some say looking up with your eyes to the 3rd eye helps  
Amnesia: Try to forget your body. Forget the physical universe  
Pretend like you are moving your astral arm. And you could try any OBE exit technique  
All of these could also induce an OBE. If they do, great, but their actual purpose is to help in conscious falling asleep.
 
- 4. Anchors
In order to remain conscious while your body falls asleep, it's recommended to have an anchor to focus on. (In past posts I used the word "anchor" as being a trigger for a state of consciousness. To avoid confusion, I use in this post "hypnotic trigger" for that instead). 
- Anchors:
any mantra works but for our purpose I would use sth like "mind awake, body asleep" so you also benefit from its affirmative effect. Awareness itself. just try to remain conscious Any trance deepeners The True Self Hypnagogic images or sounds counting your breath chakras any sensations  visualizations  
- 5. FILD
Finger induced Lucid Dreaming. It is usually used as a form of DEILD (or WILD) in order to induce a lucid dream. The technique is very effective at keeping you awake while your body falls asleep. Lucid dreamers use it to lucid dream, but we can just as well use it for general conscious falling asleep. I actually believe that this might be the key for conscious falling asleep (in combination with the other points I wrote).
You alternate slightly moving your middle and index finger of one hand. As if playing piano. The movement must be extremely tiny. Just keep doing it and decrease the range of motion. Eventually your fingers shouldn't be moving any more at all (or only less than a millimeter). But the information to move is still delivered to your fingers. The tendons and muscles might be moving or tensing slightly. You find more detailed tutorials on the internet, like:  https://www.dreamviews.com/induction-techniques/36683-finger-induced-lucid-dream-fild.html And on reddit are countless FILD threads as well, including impressive success stories.
You could say FILD, is just another anchor. But I believe it is more powerful than other anchors. Actually moving a body part seems to keep the mind more awake (perhaps by activating an additional/different brain region). And the movement is so tiny that it doesn't prevent your body from falling asleep.
For the purpose of lucid dreaming, FILD is usually only done for 20-120 seconds (then you should just fall asleep and try later again). But we will just keep wiggling until we made the transition.
 
- 6. Reviewing the keys
The following points are the most significant. Most monks are not aware of them, that's why we can achieve sleep yoga quicker.
REM core without SWS MANY alarm clocks Gamma brainwave training Reverse Blinking  awake/asleep threshold tools (hand up, sitting + no head support) Trance deepeners FILD   
Our goal is that the body falls asleep, while retaining consciousness. For that to happen the body must be tired (which is achieved by the many alarm clocks, when they wake you up, your body is still in sleep mode and wants to return as quickly as possible. And by reverse blinking, trance deepeners and by sleep deprivation, in case you end up being sleep deprived) while your mind must be alert (which is achieved through the "lighter sleep" tools and anchors). To achieve that, some astral projectors, would go for one night without sleep (body tired) and then trink coffee (mind alert) before going to sleep the next day.
 
- 7.  Simplified Technique Overview
Upon waking you do either of these (or a combination):
Just try to remain conscious while your body falls asleep awake/asleep threshold tools Trance deepeners focus on anchors FILD  
- 8. Tips 
You can also experiment with using strong intention. Jus don't allow your mind to fall asleep.  You need balance between concentrating too tightly and too loosely If you notice you are about to lose consciousness, open your eyes. Regain consciousness and then close them while using your hypnotic triggers. This sudden fractionation could be enough to send your body one step closer to sleep whlile retaining consciousness  You can switch between sitting and lying during your REM core Reverse FILD: Suddenly stop the finger movements and pretend you fell asleep. https://www.dreamviews.com/wake-initiated-lucid-dreams-wild/101305-reverse-fild-technique-100%-success-out-4-attempts-so-far.html When you can't fall asleep during your REM core, keep being conscious and see it as awareness practice, thus no time is wasted It's very easy to end up half-heartedly doing the technique upon waking up and then very quickly fall back asleep. When you wake up, strengthen your intention and determination first.  
 
Chapter 3: Daily Practices - 1. Conscious falling asleep (during your REM core)
- 2. Perfect concentration
When you are very alert and have perfect concentration you produce more gamma brainwaves. Spend every day 5-10 min of perfect forced concentration. Don't allow thoughts. Don't allow anything other than what you are focusing on. 
I usually focus on being extremely alert. Alert of whether there are thoughts. If a thought appears immediately cut it off. Don't even allow subtle thoughts. 
You can also listen to gamma brainwave entrainment at the same time.
- 3. Relaxed awareness 
Spend every day 5-15 min doing relaxed awareness. The objective is to stay aware. And allow everything to happen.  Allow all thoughts and passively observe them. That's alpha brainwaves (and some theta).  But don't lose your awareness. Aim for zero lapse of awareness. That's the gamma (and beta) brainwaves.
This is the sate of mind you need during conscious falling asleep. Relaxed and passive, yet uninterrupted awareness.
 
- 4. ADA periods
Doing all day awareness (ada) surely helps for conscious falling asleep but I don't think ada is worth the effort. Effort/Benefit ratio is poor. 
Instead, I recommend you do ada only for a short period - like 2 to 10 minutes - around 1-3 times a day. Perhaps while driving, cooking, exercising. Just do your normal activity while trying to stay conscious.
 
- 5. Binaural beats during the day
All the above practices develop your gamma brainwave skills. Additionally you can listen to gamma (and other frequencies) brainwave entrainment while doing daily activities like reading, cooking, etc. I wrote about that here: 
 
- 6. LOA Visualizations 
Visualize everyday for 1-3 min how you are successful at sleep yoga. Know that this is true. If your memories say otherwise, regard them as false memories.
You can apply all LOA stuff for sleep yoga. Here i mentioned some more LOA stuff: 
 
 
- 7. Trance 
Trance practice is not required but can be helpful.
- 7.1 Procedure
Strengthen your intention and LOA visualize how your session will unfold Get to your awake/tired sweet spot: (Reverse Blinking, hypnotic trigger, suggestions) Body relaxation: body scan, progressive muscle relaxation, tensing/relaxing muscles, visualize a light relaxing your muscles. You could also stretch, move and massage some muscles beforehand) Mental Relaxation Hypnotic suggestions Trance Deepeners and using your Hypnotic Triggers Listening to Guided Hypnosis or freestyle.
0-60 min each day, as you believe necessary.
 
- 7.2 Tips
body and mind relaxation is crucial. it is the foundation for altered sates. Don't wave them aside, thinking they are not worth doing. I made that mistake and wasted a lot of time therefore. Once I realized the importance of body relaxation, I spent a few days - 2-4 hours each day - only trying to relax the body.  The objective is to get alpha and theta brainwaves. So practice when you are tired, because then it is far easier to enter these brainwaves. Find your sweet spot, of tired enough but still able to resist falling asleep. Exhaustion. It has a similiar effect like being tired. Hypnotic suggestions are more easily absorbed and it is easier to surrender into trance. Here I wrote more about exhaustion, including it's value in terms of enlightenment:  Use hypnosis (see my hypnosis thread) Use brainwave entrainment   
 
Chapter 4: Stages of Progress  
- Stage 1
Getting close to the awake/asleep threshold for brief moments, but then being immediately snapped back
- Stage 2
Able to stay conscious while the body falls asleep. But after a few moments, you either lose consciousness or are snapped back.
- Stage 3 
Able to reliable stay conscious while the body falls asleep (during your REM core of course) and smoothly transition into a lucid dream.
- Stage 4
Able to enter the void. No, or almost no sensations of your body left
- Stage 5
Able to remain in this void during your whole REM core (both light sleep and REM)
- Stage 6
You stopped your segmented sleep schedule. You can retain consciousness while sinking into deep sleep, but are not able to hold it there for long
- Stage 7
Able to stay conscious during the whole night
- Stage 8
Able to enter epsilon brainwaves during deep sleep without losing consciousness 
- Stage 9
Able to enter the exact same depth, in your meditation during the day, when you are not tired.
- Stage 10
Able to do that in less than 5 minutes.
- Stage 11
Able to do that while sitting
- Stage 12
Able to do that while walking. You are able to split your consciousness. One part is astral projecting on Mars, while a small portion of your consciousness remains in your physical body, cleaning the kitchen.
 
 
Chapter 5: Resources and Notes - 1. Resources
There is not much information out there about Dream Yoga.
- In this post I mentioned it a bit: 
 
- Books:
Dream Yoga by Andrew Holecek The Tibetan yogas of dream and sleep by Tenzin Wangyal Dreaming Yourself Awake by B. Alan Wallace. - Forum posts: https://www.dreamviews.com/beyond-dreaming/142072-exploring-delta-sleep.html
- A Website: http://www.swamij.com/yoga-nidra.htm
 
- 2. Depth of Sleep Yoga
Some reports of being conscious during sleep, don't appear as fantastic as one would expect. I guess it's the same as with psychedelics. The average person might take 700 ug of LSD without getting nondual, while a spiritual seeker might get completely blown away by 300 ug. How deep your mystical experiences are (for psychedelics and sleep yoga alike) depends on many factors but the biggest are:
your baseline consciousness  self-inquiry / contemplation skills surrender skills intention (for pyschedelics, there are some more, like personal tolerance etc).
 
- 3. My progress so far
I had tried WILD a few times a year ago with zero success.
I have done quite a lot of meditation during the past 2 years. But I don't think this is required or provides a huge advantage compared to someone who hasn't done any meditation so far. A few months of the above-mentioned Sleep yoga practice, is more valuable in terms of sleep yoga progress than 3 years of meditation.
I started my sleep yoga practice around 3 weeks ago. My attention has been mainly on figuring out the right technique/schedule rather than trying to actually achieve sleep yoga (but I did try, of course). Now I'm finally somewhat satisfied with the technique, so the real practice starts tomorrow.
So far I'm roughly at progress stage 1. 
I'm gonna keep updating.