SCS.E | The Stages of Sleep |

SCS.E | The Stages of Sleep

Ah, sleep, one of our favourite past-times. As I’ve said, sleep is incredibly important and we spend up to a third of our lives doing it, and while you’re sleeping there is a lot going on in your brain, not the least of which is controlling your body and commanding it to stay in bed so that your dream adventure of hiking Mount Everest won’t turn into you climbing onto the roof and planting a flag on your chimney while you’re still sleeping.

Perchance, to Dream

There are two basic types of sleep: rapid eye movement (REM) sleep and non-REM sleep (which has three different stages). Each is linked to specific brain waves and neuronal activity. You cycle through all stages of non-REM and REM sleep several times during a typical night, with increasingly longer, deeper REM periods occurring toward morning.

Stage 1 Non-REM Sleep

Stage 1 non-REM sleep is the changeover from wakefulness to sleep. During this short period (lasting several minutes) of relatively light sleep, your heartbeat, breathing, and eye movements slow, and your muscles relax with occasional twitches. Your brain waves begin to slow from their daytime wakefulness patterns. You know how when you’re fighting to stay awake and your eyelids keep getting heavier and heavier? That’s your brain ignoring your desire to stay up and watch cat videos til two in the morning.

Stage 2 Non-REM Sleep

Stage 2 non-REM sleepis a period of light sleep before you enter deeper sleep. Your heartbeat and breathing slow, and muscles relax even further. Your body temperature drops and eye movements stop. Brain wave activity slows but is marked by brief bursts of electrical activity. Have you ever been drifting peacefully off into sleep while sitting up and you suddenly snapped awake just as you were nodding off?

Some scientists think that this is an evolutionary trait that is a hold-over from when our most distant ancestors still lived in trees. If you sleep in the crook of a tree, you certainly don’t want to fall out and slam into the ground or into the jaws of whatever hungry predator is waiting for an easy snack to drop to the ground. So, as your muscles relax and your head dips and your shoulders slump, the still active part of your brain senses that you’re starting to move and sends warning signals out to your body.

In our ancient ancestors, this kept you from sleep rolling out of the tree. Today, it’s more about keeping you from sliding off the sofa or banging your head on your desk. You spend more of your repeated sleep cycles in stage 2 sleep than in other sleep stages.

Stage 3 Non-REM Sleep

Stage 3 non-REM sleep is the period of deep sleep that you need to feel refreshed in the morning. It occurs in longer periods during the first half of the night. Brain waves become even slower, and your heartbeat and breathing slow to their lowest levels during sleep. Your muscles are relaxed and it may be difficult to awaken you.

REM Sleep

REM sleep first occurs about 90 minutes after falling asleep, and this is when things start getting really interesting. Your eyes move rapidly from side to side behind closed eyelids as mixed frequency brain wave activity becomes closer to that seen in wakefulness. Your breathing becomes faster and irregular, and your heart rate and blood pressure increase to near waking levels. Most of your dreaming occurs during REM sleep, although some can also occur in non-REM sleep. Your arm and leg muscles become temporarily paralyzed, which prevents you from acting out your dreams – again, no climbing Everest or trying to swim to Australia. This is also the period during which your brain performs maintenance like memory consolidation.

Who knew that your brain was so busy, even while sleeping? But what about the processes that regulate our sleep? How do those work?

Curriculum Reference Links

Biological World / Systems and Interactions / 6: Students should be able to evaluate how human health is affected by: inherited factors and environmental factors including nutrition; lifestyle choices; examine the role of micro-organisms in human health

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1. Aquarius is the the world’s only permanent undersea research station.

2. Most missions last about two or three weeks.

3. Fabien Cousteau, grandson of Jacques Cousteau, beat his grandfather’s record month-long underwater expedition by spending 31 days on the Aquarius Reef Base in 2014.

4. The lab is used by NASA, the US Navy, and researchers and educators from around the globe for training and research.

5. The internet connection is better in the Hab than at many places above the water.

6. You have to swim underneath the facility in order to enter it.

7. Crew members are called aquanauts (NOT aquaNUTS!)

8. In 1994, a crew of scientists and divers had to evacuate Aquarius and climb up a rescue line to the surface in 15-foot seas after one of the habitat’s generators caught fire.

9. Aquarius was featured in the comic strip Sherman’s Lagoon in 2012.

10. The Hab was originally built in Texas.

10 Fun Facts: Coral

1. Reefs usually grow up on the east shore of land masses.

2. Parts of a coral reef can be harvested to make medications to treat cancers and other illnesses.

3. A coral reef isn’t a single organism; it’s actually a community of life that lives and thrives in one location.

4. Only about one percent of the world’s oceans contain coral reefs. That’s about the size of France.

5. Coral reefs are the largest biological structures on earth.

6. Corals are related to jellyfish and anemones.

7. There are over 2,500 species of corals. About 1,000 are the hard corals that build coral reefs.

8. Reefs grow where there are stronger wave patterns and currents to deliver food and nutrients.

9. The Great Barrier Reef is 500,000 years old.

10. Most coral reefs grow just about two centimeters per year.

10. Most coral reefs grow just about two centimeters per year.

10 Fun Facts: Invasive Species

1. To be considered invasive, a species must adapt to a new area easily. It must reproduce quickly. It must harm property, the economy, or the native plants and animals of the region.

2. Some invasive species are introduced accidentally, but others are brought deliberately.

3. Ship ballast water transports between 3,000 and 7,000 foreign species daily around the globe.

4. The total loss to the world economy as a result of invasive non-native species has been estimated at 5% of annual production

5. Invasive species have contributed to 40% of the animal extinctions that have occurred in the last 400 years.

6. Rodents are some of the worst invasive species.

7. There are an estimated 50,000 wild ring-necked parakeets in parks across London and southeast England.

8. Black and Norway rats annually consume stored grains and destroy other property valued over $19 billion.

9. Northern Pacific seastars reproduce very quickly. In one area where they were introduced, their population reached an estimated 12 million seastars in just two years.

10. Starlings were introduced to New York in the late 1800s, as part of an attempt to bring animals that were mentioned in Shakespeare‘s work to America.

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