Anatomy of a Night’s Sleep: What Really Happens When You Are Sleeping
On a person with a normal sleep cycle the brain passes through 5 sleep stages during the night. They have been identified by measured changes in brain waves. The stages repeat themselves up to 5 times per night, each one lasting approximately 90 minutes.
Stage 1, lasts a few minutes. Here you are falling asleep. Your eyes move slowly and your muscle activity slows down. Some experience sudden muscle contractions, preceded by a sensation of falling.
Stage 2, This sleep phase is identified by, what scientists call “sleep spindles’. Eye movement stops and your brainwaves, heart rate and breathing becomes slower as you go into deep sleep.
Stage 3 & 4, The brain waves continue to deep into large slow waves. You have now reached deep sleep. This is the phase where you might start to walk or talk in your sleep.
Stage 5, is the REM (Rapid Eye Movement) phase. Eyes move rapidly, heart rate and breathing increase and this is where you experience your most vivid dreams. As the night continues your REM phase lengthens, which explains why you dream so much in the morning. You muscles are relaxed almost to a state of paralysis – otherwise you might just act out you dreams. The paralysis keeps the body safe.
A person who has been diagnosed with Narcolepsy, usually has had a Multi Sleep Latency Test (MSLT) where all sleep activity – brain waves have been recorded using electrodes, pulse tester, and video recording. When I go to sleep, I pass through the first phase very quickly – if I have not fallen asleep within 5-10 minutes, at this point in my life, I get slightly bored. Needless to say it only happens once in a blue moon. Then I skip 2,3 and 4 and more or less directly (3-15min) into stage 5, the Rapid Eye Movement phase and the body continues to be active. As the night continues, I wake up several times every 2-3 hours, but in the morning I have always managed to get some rest. Perhaps because the stages have by this point lengthened themselves to the point it squeezes in some deep sleep. So, the cause of narcolepsy is the disturbed night-time sleep and the EDS (Excessive Daytime Sleepiness), Hallucinations, Automatic behavior and possibly also Sleep Paralysis and Cataplexy are the symptoms.