Lucid Dreaming - Sending a Signal to the Waking World

Lucid Dreaming seems to be a bridge between the waking and dream worlds. You are dreaming, yet you are conscious of dreaming and capable of having rational thoughts during a jumbled dream.

Being lucid doesn't mean that you have full control over your dreams, despite being aware that I'm dreaming I still find that I am compelled to "play along" with the dream that I'm given. So, for example, if I find myself dreaming of a street scene, I can't magically transform it into countryside. In order to change the scenery I have to make the change fit into the story somehow, even if the scene-change is something as crude opening a shop door and "knowing" that it takes me to the countryside.

All this is wrapped in the fact that (for me at least) lucid dreaming is a constant struggle to remain lucid, it doesn't take much to lose lucidity and slip back into a normal dream. 

So when I suggested sending a signal from a dream in this blog-post, I thought it unlikely that I'd ever be able to remain lucid and have the presence of mind to consciously send a signal to the Zeo Raw Data (via ZeoScope) marking the lucid dream.

I'd been briefly practicing what sort of a signal to use before going to sleep every night, hoping that it'd stick inside my head if I was fortunate enough to have a lucid dream. Given that the signal has to be based on eye movements I was fairly limited in what I could do, but the practice sessions showed me that flicking my eyes from side to side just seemed to produce a very noisy signal and something that could be interpreted as EMG noise from my forehead, so I settled on eye movements to the right, then centre, which produced a nice peak on the raw EEG data (it is this type of peak that the Zeo filters to use for its EOG signal).

Because the eye movements were forced as far right as I could manage the amplitude of them rose above the normal eye movements of waking and REM. 

(Normal eye movements during a period of REM (right to centre first, followed by left to centre)

On Wednesday night I became lucid in a dream and managed to stop and send a signal using my eyes that was picked up by the Zeo.

The first thing that I remember about the dream was that I was late to get to a party and I still had to stop off and buy a bottle of something to take along. I lifted up and flew along the coast of the Thames Estuary not far from where I live. 

This was the thing that prompted me to become lucid. Flying is such a break from the everyday laws of physics that it jolted me into realising that I was dreaming.

So, I went along with the dream, flying to the party but stopping off at a small stone-clad Welsh off-licence (I have no idea why I ended up in Wales). As I landed and my feet touched the ground I remembered that I was wearing the Zeo headband and recording the raw data, so I darted my eyes sharply to the right and centred them again.

Then I thought, "That's just one, maybe it'll get lost in the other data", so I repeated it 5 more times, then bought my wine and Jaffa Cakes, lifted into the sky and headed for mainland Europe (where the party was apparently).

Shortly after arriving at the party (which turned out to be in a 1970s church hall), I woke up and glanced at the clock before falling asleep again.

In the morning I found it easy to see the signal that I'd recorded. The peaks were a lot larger than my typical eye movements. The first peak is my initial signal, then after a pause I gave 5 more right-eye movements.

So, not as significant as a signal picked up by SETI but still, this is a signal from the dream-world to the waking world. It actually reassures me because several people have asked me, "How do you know that you're not just dreaming that you know you're dreaming?" implying that lucid dreaming is itself a dream. This shows that it isn't. At the time of the signals, I remembered that I was actually asleep in bed and not outside an off-licence in Wales and although I was still standing on the cobbled street and not able to sense the waking world I was able to make an impact on it via this signal.

From the Zeo raw data it seems that a broken night played a part in triggering this dream, and I suspect that respiratory arousals were the cause again as I wasn't wearing the Rematee belt. A rough breakdown of the time surrounding lucidity is as follows...

• 04:34:45 Woke from a long stable period of N1/N2 (light) sleep
• 04:39:15 Entered REM (from wake)

Repeated awakenings and a mixture of N1/N2 and REM until... 

• 05:00:15 Entered stable REM
• 05:03:26 Began to signal lucidity
• 05:03:37 Gave last eye movement of lucidity
• 05:06:14 Woke and looked at the clock before going back into REM again
• 05:11:14 REM ended

So this places my lucid dream within REM, which was the subject of speculation for years until Stephen LaBerge confirmed that lucid dreams are actually REM dreams. 

Jeff Warren also has a good explanation of the technique in this exerpt from his book, "The Head Trip". 

Stephen LaBerge, William Dement, Lynn Nagel and Vincent Zarcone took things a lot further and even recorded morse code signals from a lucid dream via muscle-movements.

I'm still not any closer to seeing a trademark brainwave pattern of lucid dreaming, but I suspect that this is due to the single site EEG. 

I'd like to practice this further and if I'm fortunate enough to be able to do this again I'd like to try to repeat the signal every 60 seconds (as it appears to me in the dream), or at key points in the dream (such as taking off and landing, meeting a person etc etc) it would be interesting to see if these signals can be used as markers to chart the flow of time through a dream.  

Lucid Dreaming - Wake & Back to Bed

A few nights ago I had a spontaneous lucid dream.

The curious thing about this is that I can pin-point when it happened on my hypnogram, so I thought I'd share it on here.

First let's take another look at a near-perfect hypnogram. This is from my son's sleep and is about as near to textbook as I think possible in real-life:

Adults will typically get less REM than this, but the pattern should still be the same. Slow-wave (deep) sleep in the first half of the night, decreasing as the night wears on then increasing amounts of REM into the morning.

In my previous post about Lucid Dreams I mentioned a method of inducing lucid dreams called "Wake and Back to Bed". Essentially it goes like this: 

1. Go to bed at your usual time
2. Set an alarm for the early hours (say 4am)
3. Wake when the alarm sounds
4. Get out of bed and read for an hour or so
5. Return to bed

This has the effect of causing your REM sleep to be concentrated in the period when you've returned to bed (the idea being that your body is now screaming out for the REM that it should have had when you were awake for the hour). The period of being awake should also "sharpen" your conscious mind so that it is more likely to be aware of the dreamworld when it next encounters it.

For my lucid dream, this happened by accident as is good evidence that the method works.

I spontaneously woke at my usual weekday alarm-time which was ridiculously early for a Saturday morning, so took off the Zeo headband, flicked through the news and Twitter on my phone (still in bed), then decided to have another go at sleeping.

I didn't get a mass of REM in this second sleep, and most of the "sleep" that I did get was light dozing, but there was an isolated period where I slipped into REM and had a lucid dream. This can be clearly seen on my Zeo hypnogram for the night:

I know that it's boring listening to other people's dreams but to give you an idea of how lucidity evolves I'll outline it...

I was in a restaurant in France. I was sitting with my extended family who took up most of the restaurant. Then I realised that people were "tutting" at me. Somehow I'd managed to offend the restaurant owners. 

It seemed odd. After a while the tutting turned to people talking about me as if I wasn't there. I looked down at my plate and realised that the tables were full of rain. Again, more oddness. Water was actually flowing around our plates as if we were eating in some sort of water feature.

It began to make less and less sense, then I looked at the faces of the people who I thought were family. I didn't recognise any of them. 

Then it hit me: people's faces changing, changed laws of physics, feeling of conspiracy... it was a dream. I still wasn't sure, so I calmly did a "reality check" (Something that I don't get to do in dreams that often)... I counted the fingers on one hand. Five... so it must be real. I looked at my hand again and saw an extra finger! 

Ha! Definitely a dream then. 

I got up to leave and (almost symbolically of the dream trying to re-capture me) found that the people in the restaurant were trying to prevent me from going. I managed to get out of the door which seemed to pull me back like a magnet, but eventually I was in the street outside. 

More symbolism: The world outside was definitely the dreamworld, it was a town mixed with cartoon imagery complete with giant cartoon people using skyscrapers as stepping stones. 

Anyway, I won't go on, but as lucidity came on slowly I was able to stay calm and stay in the dream, rather than waking. Eventually after a couple of periods of forgetting I was dreaming and becoming lucid again, the dream won and settled into a normal dream. The dream covered about 3 days, but as you can see from the solitary green bar on the hypnogram, it lasted not much more than 5 minutes.

This is definitely a method that I think is worth exploring further.

Lucid Dreaming

 

Imagine that as you read these words you hear a voice from nowhere telling you "You're dreaming..."

You may even tell yourself that you just imagined it, but what if you listened to the voice?

What if you then looked around and saw clues that all was not as it seemed?

What if you then realised that you were actually dreaming? You'd realise that you were essentially a character in a story that your sleeping brain was dreaming up.

As the author of this dream you'd them be able to control aspects of it. You'd be able to communicate with your sleeping-self and in essence become a god in a universe that you created.

Crazy? Maybe. Impossible? No.

This happens to people, and it happens to me...

I was dreaming. I couldn't remember how I got there but I was trapped in a room with no doors and no windows. There was, however, a large mirror on the wall. 

Something changed: I stopped worrying about getting out and instead tried to work out how I'd managed to get there in a room without an entrance in the first place.

"It's got to be a dream", I told myself.

"Well, if it's a dream then I should be able to walk through the mirror and escape."

So I tried - face first...

... and after a bit of pushing I found myself in a stairwell on the other side of the mirror. "Yep, definitely a dream" I thought as I became aware of the other me - the "real me" asleep in my bed.

"Wow! I'm dreaming". I did the obvious thing and tried to fly my way to safety; slowly I was hauled upwards by the shoulders and flew for about 300 yards. As I get more involved in the story I somehow started to forget that it was a dream and after a few more episodes of realising and forgetting that I was dreaming it settled back down into a normal dream.

Sounds familiar? "The Matrix"? Pretty much, although it's an older idea in the world of philosophy. It's essentially a scaled down version of Gnosticism. In Gnosticism our world is the dream-world and there is a "real world" in which our awareness exists watching us play our parts in the "here and now". Like a set of Russian Dolls, we are also able to create a fake world in which we can lose ourselves in the experiences that it offers.

For some people these dreams happen spontaneously, meaning that they don't have to prepare or practice in order to get to hame them. Others can only dream of having a dream like this (poor choice of words really). The idea of a normal dream is mind-blowing enough when you think about it: every night we go to sleep and lose our sense of identity. We lose sense of the passage of time and we forget that we are The Dreamer Dreaming, we actually feel as if we are the character in the dream...

...but with a lucid dream we adopt a dual consciousness: our real-life identity returns and we can watch the dream from the vantage point of that identity from the comfort of our bed knowing that whatever happens we are safe, we can take more risks in the dream, we can have fun with the story rather than fear it, we can even shape the dream-world, yet we can also simultaneously adopt the vantage point of the dream characters and get involved in the story. You are both the Dreamer Dreaming and the Dreamed.

My first lucid dream was a spontaneous one and it happened on the night that I had three episodes of sleep paralysis. The sleep paralysis was the trigger that told me that I was dreaming. From that moment on I was in the dream, but still able to reason with the dreamer part of me.

Lucid dreaming isn't just an interesting sleeping-habit, it has actually been used to help people control re-occurring nightmares.

How can you make lucid dreams occur?

If you aren't one of the lucky ones that have had lucid dreams spontaneously (or you want to able to increase the frequency with which they occur) then there are a few things that you can do to help turn a normal dream into a lucid one:

Dream worlds seem to be comprised of disjointed scenes with the brain doing its best to link them together in a narrative, as such the rules that govern the dream world can differ from scene to scene, hence if you check, you may have 10 fingers one moment, then the next moment 11 when you check again. This sort of clue should be enough to alert you to the fact that something isn't right and that you are in fact dreaming.

Most people talk of performing "reality checks" where throughout your waking day you constantly check whether you are awake. You can simply ask yourself if this is a dream, or you can perform some checks to see if you are really awake.

These sort of "Reality Checks" don't really work for me, instead I question my surroundings. Do this during the day and it should carry over (sometimes) into your dream.

The big pointer to me is a lack of continuity, such as the night when I entered REM sleep as soon as I closed my eyes (confirmed by Zeo)...

 (Click for larger image)

...I was suddenly in the back of a car that was being driven along a mountain road, I had the sense that we were late for something and possibly being chased but my first thought was, "...but I was in bed a moment ago, how did I get here?". That questioning was enough to shatter the illusion and I became aware that I was still in bed (even what position I was sleeping in), and yet I was still in the dream. So Chitty-Chitty-Bang-Bang style I was able to make the car fly to the meeting that I was late for.

When you wake from a normal dream, you may well kick yourself because something in the dream was so odd that you should have realised that it was just a dream. These are the sort of things that you can look out for to act as a prompt for you to question your surroundings.

Question everything:

• How did you get where you are?
• Who are you with? 
• Why are you there?
• Is time flowing as it should - were you older a short while ago?
• Can you fly?
• Do doors take you where they are supposed to? Actually walk through a doorway rather than assume you have just walked through it. (For me, doors usually take me onto the roof of a building).

Other things to look out for are sounds that don't belong there. I've had several lucid dreams that have been triggered by noises that make their way into the dream. Examples of that are:

• During the summer I slept with the window open one night. I dreamed that I was standing beside a really busy airport runway with planes rushing by every few seconds or so. As I listened to the noise I realised that they weren't planes but they were actually cars going by my house. This triggered a lucid dream.
• I was dreaming that I got out of my car, then I heard myself growling... "Oh great, now I'm a werewolf", I thought to myself. I then listened more to the growling that I was making and realised that it was actually snoring, from there it was an easy jump to realise that I was actually dreaming and could hear myself snoring. The dream became lucid from that point.

Several devices make use of this principle.

I've already mentioned Dan's ZeoScope software elsewhere in this blog. This works in conjunction with the raw data from the Zeo Bedside unit. When you have been in REM sleep for a certain time, ZeoScope plays your choice of mp3 to you. This then "leaks" into your dream as a signal to you.

There are also several iPhone apps that do something similar, although they only guess at when you are likely to be in REM as they have no way of telling. DreamWaker and Dreams Controller are both good examples of this. Dreams Controller also goes to the lengths of prompting you to perform reality checks whilst you are awake. The first time I tried these apps I became lucid, and a certain school of thought says that is likely due to the "beginners luck" effect where your anticipation and expectation of a lucid dream causes it to happen.

To a degree, the principle of a stimulus leaking over from the real world to the dream world also applies to sights as well as sounds.

The NovaDreamer is a device that looks like a sleeping mask, but with red LEDs built into it. An infra-red LED detected when your eyes are moving (hence you are in REM sleep) and then flashes the red LEDs to alert you. In your dream these red lights can become anything from a police car to a volcano. Your job is to realise that anything flashing red in your dream is a signal that you are dreaming. 

I've had limited success with the NovaDreamer and a similar device called the REM Dreamer, although I found that they often woke me up.

Other tips:

• No alcohol - If you do achieve lucidity then (for me) it is always short lived and usually becomes an episode of sleep paralysis.
• As you drift off to sleep really be aware of your surroundings. Note your bedroom, your position in bed etc
• REM deprivation helps. Maybe this is because when you next achieve REM it will be much nearer to the start of sleep meaning that you can carry the awareness mentioned above over to the dream.
• If you become lucid, don't get too excited otherwise you'll wake up.
• If you become lucid, keep reminding yourself that you are dreaming otherwise you'll forget.
• Read about lucid dreaming before you go to sleep, surprisingly this can help as you may dream about lucid dreaming (which will then be a pointer to you in your dream)
• Set an alarm for around 3am. Wake up and actually get out of bed, don't just doze, you need to be fully awake. You could read for a short while (maybe an article on lucid dreaming would help), then return to bed. This time of the morning is when REM sleep is increasing. This time awake should allow you to enter REM pretty quickly, almost with a vengeance.

Supplements to aid lucidity?

Pills and potions to aid dreaming are nothing new; many works of art such as this fantastic watercolour by John Anster Fitzgerald painted 1857-1858. I have a copy of this on my wall, and yet I am not certain of the name. I suspect that, like Fuseli's work, it is called "The Nightmare", but I've also seen it listed as "The stuff Dreams Are Made Of", although  I think that name may relate to later versions where the bottles (probably containing opium) have been omitted.

Opium aside for obvious reasons, there are a number of nutritional supplements that have an effect on sleep and consequently dreams.

I've tried a few supplements to try to reliably encourage lucidity, with some partial success. It's partial because nothing seems to do this on it's own but with a little preparation they seem to help, but proceed with caution (don't treat anything you see on the internet at automatically safe - my words included. Look both ways before crossing, chew your food etc etc), and research any supplements for yourself before you decide to use them. 

A short word on dosage

Melatonin: the dose given in the BNF is deemed to be the most effective dose. I am well aware that I am taking more than that, although singles doses as high as 10mg are on sale and studies of daily doses of up to 75mg have been conducted (MacFarlane et al.).

Vitamin B6: Although 200mg doses are on sale in the UK, it is not recommended to take them on a long term basis as they can cause side effects which appear to reverse when the dose is stopped

Yesterday (in the real world) I was driving for 350 miles and listening to audiobooks discussing consciousness, quantum physics and Gnosticism. I realised that this stuff would be floating around my head during sleep as my brain processed the events of the day, so I thought there would be a good chance of lucidity that night. 

This is the routine that I've found seems to help:

45 mins before bed: 5mg time release Melatonin
30 mins before bed: 200mg Vitamin B6
When in bed:  1mg Melatonin (not time release)

It is known that too much Melatonin will be counter-productive and cause you to wake up. I think my method actually makes use of this effect. The British National Formulary sets 3mg of time-release Melatonin as the correct dose for an adult over the age of 55 (Not usually prescribed for people below 55) Generally 0.25mg of instant release is enough to initiate tiredness and hence sleep - the sustained release version ensures a trickle dose throughout the night. 

I usually find that I wake up fully after a few hours. This is when I then take a further

1mg Melatonin (not time release)...

...which sends me back to sleep within about 20 minutes. That's it. I normally find that will give me lucidity or sleep paralysis (which can be converted to a lucid dream which may even take the form of an OOBE - Out Of Body Experience).

It's not a guaranteed method, but on the nights that I've tried it (a few times a month for several months), usually something has happened, even if the effect was short lived. I suspect that lucidity would last longer if I were calmer when I realised I that it was a dream. 

Update on Saturday, March 17, 2012 at 2:51PM by Hypnagogia Blog

I had some experience of the "Wake & Back to Bed" method of inducing a lucid dream.

http://hypnagogia.squarespace.com/blog/2012/3/17/lucid-dreaming-wake-back-to-bed.html

Update on Friday, May 11, 2012 at 10:15PM by Hypnagogia Blog

Lucid Dreaming via a disturbed night...

Sleep Paralysis as a Result of Nocturnal Disturbances and Respiratory Events?

During one lucid dream I was able to signal to my monitors that I was actually in a lucid dream...

Lucid Dreaming - Sending a Signal to the Waking World

Sleep Paralysis

 A sound wakes you up in the night. You sense that you aren't alone anymore - something is there with you.

You rationalise: someone has come into your bedroom, that must have been what the sound was. Cautiously you turn your head to see if you can see them, but it doesn't move!

You panic.

The intruder is pushing down on your chest making it hard for you to breathe. You can't take a proper breath, let alone call out for help. You might just be able to make a slight sound in the back of your throat. You can't even move your head down to see who (or what) is crushing you.

There's a noise in the room too - ripping sounds, it's loud as if it's right in your ears. All sorts of thoughts race through your mind, before you pass out with fear. Then it's morning and all is well. There's no sign of intruders, no damage to your body.

What I've just described was an episode of Sleep Paralysis, and as scary as it is, it isn't harmful.

Most would class this as a strange night, and to be fair it is.  However it actually happens to some people, and more accurately, it happens to me.

Folklore has many "explanations" for this, but they largely centre around applying cultural beliefs over the top of the facts. Explanations are as varied as:

• witches and old hags being the cause 
• demonic attacks 
• sexually active ghosts of both the male and female varieties (incubus and sucubus)

Many cultures have their own name and culprit responsible for Sleep Paralysis, and a comprehensive list can be found here. A more modern piece of folklore about Sleep Paralysis is that it is an alien abduction and that the noises you hear whilst paralysed are actually medical experiments that are being conducted on you. 

As the brain scrabbles to make sense of the situation it tends to fill in the gaps with dream-like hallucinations that are overlaid onto what you can see (remember that you have a fixed field of vision which is usually just your ceiling). 

In fact in my first episode of sleep paralysis (I was 12 or 13 years old) I remember that as I was trying to scream I was also remembering stories that our house was haunted. So, the logical thing for me to think at the time was that this was an attack by some sort of ghost and that I wasn't allowed to see whatever ghosts get up to in the night, so I was being held down. (Yeah, yeah, yeah. I was 12).

A nice (and rather famous) depiction of sleep paralysis is a painting by Fuseli called "The Nighmare" in which a sleeper (sleeping on her back - which is frequently the position that paralysis occurs) is being crushed by a demon-like animal whilst a presence watches in the room.

The Nightmare by John Henry Fuseli, 1781

...although a more modern take on this painting might be something like this:

What's the real cause?

When we dream, our brains are as active (if not more active) as when we are awake. Our brain is generating fake sensory input and processing it as if it were real. The only thing that stops us getting out of bed and running around acting out our dreams is that the brain induces muscle paralysis during REM sleep, with only a few essentials left un-paralysed. This is called "REM Atonia".

Ideally this paralysis is activated at REM onset, and de-activated as REM stops. But sometimes it can come on too early or switch off too late, not only can this happen at the beggining and end of a REM period, but it can also happen during a REM period if the sleeper is briefly woken in what is called "an arousal".

 
Whichever way it occurs, effectively, the brain is awake and conscious but the body is asleep.

I was chatting with a friend who confessed that she is woken by spiders in her bedroom, dangling from the ceiling and spends a while trying to get away from them before waking up fully and realising that nothing is there.

After chatting I suggested that she put a familiar object in the room, so that if she saw it when an episode of this occurred then it would remind her that is was just a type of dream and she would be able to calm down. This seems to be different from Sleep Paralysis, and I doubt that she is aware of her surroundings in the same way, so it may not be of any use, but...

I then decided to have a go at that idea myself and purchased a large copy of Fuseli's "The Nightmare", had it framed and placed in on my bedroom wall so that I would see if when I woke up paralysed and remember what was going on.

One night I was repeatedly woken by my son's oximeter, I had to keep getting up and dealing with things and then get back to bed. Each time I got into bed I found myself paralysed. The first time I was scared, as normal but the picture helped calm me down... By the third time I found it funny. I recognised the familiar feeling that seemed as if someone was deflating my muscles one by one. I then thought to myself, "Okay, your body is alseep, but you are awake".

I calmly looked around the room and decided that I would get up. I thought to myself that if my body wasn't going to bother getting up, then I would get up without it, and no sooner had I thought that then there was a buzzing crackling tearing sound and I found myself about two feet above my body looking at the ceiling.

I then moved down towards the foot of the bed, my feet descended to the ground and I was free. I could look back at my own body (I only saw my feet still in bed). Just to the left of the foot of my bed was a figure. I knew that this was the presence that I'd felt whenever I'd had sleep paralysis, but this time I could see it!

Having never left my body before I was feeling rather pleased with myself. I looked at the figure and he gestured for me to go past him. I did, straight into (and through) a mirror into the room next door!

From that day I haven't been worried about sleep paralysis, in fact I've welcomed it. I don't seem to be able to easily reproduce the feeling of leaving my body (more often than not I hear the buzzing ripping sound and the excitement wakes me before I can "leave") but I can quite easily turn the experience into a lucid dream.

With the folklore around such powerful events, there seems to be a specific term for the presence I saw:The Guardian of The Threshold. It seems that his job is to intimidate you into not proceeding until you are deemed "ready". I guess that this is similar to hallucinations, emotions and images that meditators see, and claim that their purpose is stall the meditators into staying in that particular level of meditation. 

However, for me, something seems to connect of Out of Body Experience and Lucid Dreams. It seems that I can't go through doorways in them, if I try to then I always end up somewhere else (usually on a high up place). I can go from room to room by walking through walls and mirrors easily enough, but for some reason never doors.

It's odd that now that I want it to happen more often, it seems to happen less frequently. Maybe the fear was a factor in causing it. What seems to happen is that as soon as I wake up and realise that I can't move I begin to think, "Right, let's see what we can do. Can I dream? Can I fill the room with dream imagery? Can I leave my body? etc". So the paralysis isn't the major event anymore, it's more of a gateway or a stepping stone.

Can anything help sleep paralysis? 

Speaking from my own experience, there are a couple of things that you can do.

The majority of my episodes have ocurred whilst sleeping on my back (leading me to link them with apnoeas), although I have had some episodes whist on my side (oddly, with a side-lying OOBE "I" still left my body in the same manner - chest first, then a turn to face the ceiling, then moving towards the end of the bed, then feet on the ground).

So...  

• Don't sleep on your back
• Have something in your room that you associate with Sleep Paralysis that you'll be able to see when an episode occurs. This will remind you that it's a trick and that you are safe.
• Relax if it does happen.
• Know that you are safe and that it will pass.
• Don't struggle, it seems that the more you try to breathe normally the more you are aware that you can't.
• Remember what the real cause is. Sooner or later you will either fully return to sleep or wake.