[Juris Graney]

Juris Graney  asked the Naked Scientists:
   
Hi team. Just wanted to say that I love your show, especially your podcasts, which I routinely put on while doing the house work.

My name is Juris (pronounced You-Ree) and I am an Australian living in Vancouver, Canada. My question relates to my wife, Emma.

On another note, we were also discussing dreams we had. Emma has the most vivid dreams which appear to go on for ever, her morning recollections can stretch five or 10 minutes, even with bits left out.

So when exactly do we dream and how long to dreams normally last?

Is it simply the fact that what 'appears' in our dreams, if recreated in real life, would take hours to complete and so we therefore assume that we have dreamt for a lot longer than we really have?

What do you think?

[wanhafizi]

Dream doesn't happen right away when we fall asleep.

Later stages of sleep will bring you to REM sleep. In this state, our brainwave is very active. It would seems that as if the person is wide awake. This is actually where dreams occur, and the brainwave showed how busy the brain is. A typical REM state can last 15-20 minutes.

When we fall asleep, the body is paralyzed. So, when we sleep, the mind no longer restricted by the physical body and time is no longer the same with the outside world.

Time is relative. Remember when you were kids, time seems to move very slowly. In the documentary "LSD: The Beyond Within", a experiment done with LSD. The observer reported that he felt that the duration is longer than the external time. Many of us know that marijuana also slows time down, and some of us know that cocain speed things up.

So, the timing of dreams for someone cannot be judged by the duration of their REM sleep.

[glovesforfoxes]

just for accuracy, dreaming can also happen in the non-REM stages of sleep, but they tend to be much less vivid.

[Nizzle]

just for more completeness, multiple cycles occur during a night of sleep, depending on how much hours you sleep. A full cycles lasts 3 hours, so if you sleep 9 hrs, you've had 3 REM Cycles

[Madidus_Scientia]

There's some discrepencies in this thread. According to Wikipedia a REM cycle typically lasts from 90 to 120 minutes, not 15 to 20 minutes as wanhafizi says, or 3 hours as Nizzle says.

Who is right?

http://en.wikipedia.org/wiki/Rapid_eye_movement_sleep

[Nizzle]

I wasn't talking about the REM phase being 3 hours.
An entire sleep cycle is 3 hours, of which the REM phase is only a part.

[glovesforfoxes]

hold on. i was taught and have read in many places that a single sleep cycle (moving from stage 1-4, then REM) lasts 90 minutes while the REM stage inside that sleep cycle lasts 15 minutes according to EEG readings. so for 9 hours sleep you will go through 6 sleep cycles, and a period of 6 REM cycles that would last in total 90 minutes over the course of the night. however, the 15 minutes REM stage is an average - i believe that closer to the waking time, the longer the REM stage becomes.

[wanhafizi]

I wasn't talking about the REM phase being 3 hours.
An entire sleep cycle is 3 hours, of which the REM phase is only a part.

Nizzle was right. Every sleep probably involve multiple cycles of REM sleep. It is very common that brain alternates between these states.

Some cycle will continue with another dream which seems continuous with the previous one, but some will have a completely different set of settings.

The most interesting part of REM sleep is that the more higher brain functions involved, the more you'll remember it. For example, when the dream get too weird until your conscious mind started questioning about things or a dream involved intense emotional memory, we will remember them more.

Lucid dreaming is just one of the example how this is proven. In lucid dreams, higher brain functions started to kick in. In that moment, you'll probably become conscious that you are dreaming, maybe you can control your dream, walk around, fly or do some other amazing stuff, thus everything is much more remembered because more part of the conscious mind get involved.  That's why lucid dream is amazingly more interesting, more lucid and much more clear.

[Nizzle]

I think I can induce lucid dreaming.
When I'm going to bed, I sometimes make up a story in my mind while sleeping in. And in the morning I often wake up with the feeling that the story I made up continued in my dream, but without maintaining control over the storyline.

[wanhafizi]

That's nice Nizzle.

There are many online groups advocates the world of lucid dream. There are also lots of gadgets developed to help people gaining lucidity.

In lucid dreams, you can experience anything. Flying, meeting deceased people and having sex, just to name a few. Some even discuss the use this state to practice skills such as public speaking and confronting fears.

[Nizzle]

My lucid dreams mostly don't make sense and almost always take place in a clearly off world setting ...

I may have watched too much scifi throughout my life though