This article outlines the sleep cycle, lucid dreams, and how they interact with one another.

A lucid dream is a dream in which the dreamer is aware that he or she is having a dream. One is able to manipulate, change, and control the outcome of the dream down to the smallest details. Though lucid dreaming has been practiced for thousands of years, it had not been studied as a science until the early 1960s. There are several therapeutic benefits to lucid dreaming, particularly in treating nightmares and other sleep disturbances.

In order to properly understand how to lucid dream, you must first understand the stages of sleep and how lucid dreams interact with them. To over simplify, there are a few stages of brain activity and sleep:

• Awake - you're alert, have full control of your body, and can think logically.
  
• Pre-sleep - you're tired, start nodding off, you might catch yourself suddenly jolting awake (hypnic jerk), or simply falling asleep. During this time your brain is in the alpha wave stage - also called hypnogogia.
  
• Sleep stage 1 - Your brain is emitting theta waves. During this stage you may get hypnic jerks, muscle spasms, that "falling feeling" (sometimes alien abduction).
  
• Sleep stage 2 - During stage two your brain k-complexes and spindle waves in order to keep you relaxed and in a dream state. Both of EEG phenomena have been linked to memory consolidation - a very important part of the sleep process.
  
• Sleep stage 3 - Slower brain waves still (2-4Hz). Memory consolidation still occurs here
  
• Sleep stage 4 - Delta-waves are not being emitted by your brain and you are in a deep sleep. Some dreaming occurs during this phase, but for the most part you're just asleep.
  
• REM stage - One of the most interesting stages in the sleep cycle. This is where most of our dreams occur. Your brain emits very high frequency (15-30Hz) waves with a very low amplitude. The waves seem to mimic awake, pre-sleep, and stage 1 waves. Typically if someone is awoken during this stage they will remember their dreams, but not if they were awoken naturally or in any of the other sleep stages (with exception, of course).

It is important to note that during REM sleep the brain fully paralyzes the body to prevent the you from physically acting out your dreams (can you imagine what that'd be like?)

So where does lucid dreaming fit in? During lucid dreaming, the brain wave pattern is nearly identical to the awake state. The brain is (mostly) engaged and is making decisions just like it would during the awake state. The only difference is that the body is still paralyzed. Most lucid dreamers go: awake, pre-sleep, stage 1, stage 2, stage 3, stage 4, REM, lucid dream. It is believed that this is because the wave patterns during the awake stage are so similar to the patterns during REM sleep - it is simply easier to make the transition. It is considered very difficult to go from stage 4 directly into lucid dream state.

So how can you slip into a lucid dream? There are several known techniques.

1. Write down your dreams! Write down everything that you can remember and do it as soon as you wake up. It is VERY important to do it as soon as you wake up - even if it makes no sense. Don't bother with full sentences if it's too much of a bother. The more you write down the easier it will be for you to remember them in the future. Not only that, but it will be come increasingly easy to realize that you are dreaming while IN a dream. Reading your dreams over again helps in this process - especially if you read them before going to sleep.
   
2. Stephen Laberge's technique: Figure out what time you actually fall asleep. Not what time you get into bed - but what time you fall asleep. Set an alarm to wake you 4.5, 6, or 7.5 hours into your sleep (during the middle of REM sleep). When you wake up, try to remember as much of your dream as possible. Think about the details and try to fall back into that same dream when you fall asleep. Continue to remind yourself that you are aware that you are dreaming.
   
3. Test yourself. When you are dreaming there are several things you can do to test whether or not you are in a dream.
   1. Adjusting light levels (turning on/off the light switch) is often hard for your brain to simulate while in dream state.
   2. Similarly, reading large amounts of text is difficult - not impossible, but difficult. Often times the text is different when you look back at it a second time.
   3. Some people report that clocks never change during dreams (digital and analog).
   4. Looking at your reflection in dreams will often show a distorted or blurred version of your face
4. During your awake state, consistently ask yourself whether you are asleep or awake. Some people do the alphabet test: pick a less common letter (like X or Q). Every time you see that letter, get in the habit of asking yourself if you're dreaming. Once it becomes natural to ask yourself this, you will start to do it during dream state as well.
   
5. Hypnotic suggestions - also called the "hands test." Before falling asleep, look at your hands and tell yourself that every time you see your hands you will ask whether or not you are dreaming. Tell yourself that you must remember to look at your hands the next time you see them. Do this for several minutes. Put yourself in a calm and very relaxed state of mind (it works well after meditation). Your suggestions (to look at your hands) will often carry over into your dream state. Though it takes a few hours for you to get into REM sleep, your suggestions will still be there. Just like when you tell yourself "in 3 hours I must go to the store to get more milk" - you don't need to set an alarm to remind you to get milk - your subconscious thought will automatically sound an alarm in your head *about* 3 hours later reminding you to do this. This works between the awake/sleep transition as well.

One trouble that a lot of people have when attempting to lucid dream is that they will scare themselves awake. As soon as they realize they are dreaming, they become excited and wake themselves up as a result. This is common and can be overcome with practice. Just keep trying.

Remember: when you sleep, your REM stages will always be shorter and your sleep deeper if you were physically or mentally exhausted when you fell asleep. It is very difficult to lucid dream (much less dream at all) when you're dead tired. It is best to make sure you are well rested throughout the day. Strenuous exercise before sleep is NOT conducive to lucid dreaming.

The most common time to lucid dream is early in the morning. I find that I have the most lucid dreams when I've been waking up at 6am every weekday morning. When saturday comes I wake up at 6am naturally, realize I don't have to get up for work, and then go back to sleep. When I go back to sleep, it's very easy to slip back into a lucid dream.

Dangers of lucid dreaming? Yes there are dangers, but they are not as great as one might think. In short: you're messing with your sleep cycles. When you lucid dream you are pulling yourself out of REM sleep and into an awake state - preventing your brain from doing what it does naturally during REM sleep. During REM sleep there is lots of "bookkeeping" that occurs in your brain - specifically the consolidation of memories. When you lucid dream, you aren't allowing your brain to do this - instead you're using it just as if you were awake. This is why people who regularly lucid dream find themselves tired, groggy, or scatter-brained the following day. They simply did not get a full night's sleep because they were up all night making conscious decisions.