Performance Notes
This show was particularly packed as several people have started hearing about it.
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| The pitch |
Sleep is neurologically very busy - people used to think it was a period of mental and physical inactivity used to recharge. We do recharge but it is far from inactive. In fact we only save about 50kcal by being asleep.
We have discovered 5 stages of sleep based on brain waves using Electroencephalography otherwise known as EEG. It is measured by electrical activity on the scalp produced by neurons firing in the brain.
Each neruon is too small to measure - therefore synchronous activity is monitored of millions of neurons (later corrected by an audience member to tell me that this year they have developed a system for monitoring individual neurons - apparently it is something frightful involving needles).
There are 13 billioni neurons in the brain which react to stimuli (senses) and also to internal stimuli such as meditation, relaxation, stress, sleeping, calculating or just being conscious. These are known as Spontaneous Brain Potentials.
There are many different types of brain waves:
- Delta: 3hz frequency range for deep sleep and babies
- Theta: 4-7hz, young children, tired adults and aroused/horny adults.
- Alpha 8-12hz, this is the posterior basic rhythm - awake but relaxed
- Beta, 12-30hz, active / busy / anxious
- Light Sleep - half awake half asleep (literally - 50% reduced brain activity) . Muscles slow, small amount of twitching, easily awakened. Brain produces high-amplitude slow waves. Lasts for a few minutes up to 5% of sleep time. Weird dreams as pulses of "awake waves" happen. If person is woken 80% of people will say they are not asleep at this stage.
- True sleep - lasts about 20 minutes. Breathing and heart rate slows. Body temperature drops, brain still registers slow waves but with occasional spikes known as Sleep Spindles (staying at 7hz and then spiking to 12-14hz during a spindle). This causes body to twitch and shows that either the subject is entering stage 2 or entering stage 3.
As we move into stage 3 the pons (part of the brain stem that connects to the spinal cord) signals the thalamus and cerebal cortex to star dreaming and turn off motor signals. But light, caffeine/alcohol and stress can prevent you from sleeping.
The eyes send signals to the suprachiasmatic nucleus in the centre of the brain where the optic nerves cross and then to the pineal gland (also called the third eye) which produces melatonin and affects our sleep.
For caffeine or alcohol - up to half the amount consumed can remain in your system up to 6 hours after consumption.
Stress creates cortisol which normally naturally declines toward the end of the day.
Stage 2 accounts for 44-55% of sleep.
- Deep Sleep - Brain produces delta waves (same as a baby). Dreams more common here than in previous stages but still not hugely common. Children sleep more in this stage than adults (maybe that's why they sleepwalk more? More on that later).
Stage 3 accounts for 15-23% of sleep.
- Deeper sleep - Blood pressure drops, muscles relax but blood flow increases to the muscles. This is the most restorative type of sleep..Body releases growth and repairing hormones and refreshes energy. Bedwetting, sleep walking and night terrors are more common here as this is when the brain can forget to tell the body not to respond to the dreams and so the body thinks that everything is really happening to it.
- REM - A sudden blast of activity! The brain seems awake - dreams most often remembered in this stage and you have the highest chance of dreaming. The body adds cortisol to keep the body alert for waking.
Also during sleep the digestive juices change, reproductive hormones are released (especially in women) and the kidneys shut down meaning you have more concentrated urine in the morning.
What are Dreams?
A succession of images, sounds and emotions. Humans spend 6 years dreaming. Scientists don't study the content of dreams as they are rarely remembered.
Theories on why dreams happen:
- Brain interpreting internal stimulus as projections
- Freud (boo) said they were internalised "forbidden" thoughts
- Short-to-long term memory transmission
- Processing long-term but rarely retrieved memories
- Removing junk from the brain
Animal sleep hours
Python - 18 hours
Tiger - 15.8
Cat - 12.1
Chimpanzee - 9.7
Human - 6.5
Sheep - 3.8
Elephant - 3.3
Giraffe 1.9
Records and Side effects
Longest time without sleep was 11 days (under scientific conditions without drugs) was 11 days by Randy Gardner (yeah, I know...). Started hallucinating after 4 days but still, on the 10th day, beat a scientist at pinball.
He hallucinated he was Paul Lowe (American footballer) winning the Rose Bowl and that a street sign was a person.
Normal humans don't die from sleep deprivation (although it can cause diabetes) because the human brain protects itself by a series of microsleeps where even the subject may not know s/he has been asleep.
Unless you have Fatal Familial Insomnia - a rare genetic disease - so far incurable that manifests around 30-50 and will kill you in between 7 and 36 months.
It has four stages
- Insomnia resulting in panic attacks, paranoia and phobias
- Hallucinations and extreme panic attacks
- Complete inability to sleep leading to rapid loss of weight
- Dementia and the patient is unresponsive.
People who sleep less than 6 hours or more than 9 have a death rate 30% higher than those who sleep 7-8 hours.
Calvin S Hall collected 50,000 dreams between 1940-1985 and discovered that people all over the world mostly dream about the same things:
- Mostly dreams feature anxiety or negative feelings
- 10% of the dreams are sexual
As a society we sleep on average 3 minutes fewer than in 1965 and scientists say we haven't changed much in our sleeping patterns in 2,000 years.
Any mistakes? Corrections will be credited.
