Why Do We Need Sleep? AN OVERVIEW OF ONE OF THE MOST IMPORTANT CYCLES IN OUR BODY.

How Much Sleep Do We Really Need?  The average adult needs about 7-9 hours of sleep each night.  That is seven to nine hours of an entire day spent doing “nothing”, one might say. Why waste so much time when we could be doing more important things that demand much more attention in our busy lives, right?  Wrong. The body needs sleep just as it needs food and water – sleeping gives the body a chance to grow, to recover and rebuild itself, to interpret and organize information gathered from our surroundings throughout the day, and much much more!

The Basics  So we know that sleep plays a vital role in our health and well-being, but how our brain controls it in particular remains relatively unknown…  Extensive research in the last few decades, though, has allowed scientists and other sleep specialists to develop four postulates that may help us understand this complex cycle a little better: ◦ Energy Conservation ◦ Inactivity ◦ Restorative Theory ◦ Brain Plasticity

Energy Conservation  Our body is all about saving energy:  With more energy saved, there is more energy available for important processes that take place during our awake cycles.  When we don’t sleep, our body expends a lot more energy in keeping us awake when we are not supposed to.  Our body adjusts our metabolic rate to different conditions.

Inactivity or Evolutionary Theory  Evolutionarily speaking, inactivity keeps an animal quiet and out of sight. But they also become vulnerable to many dangers.  So how does an animal stay safe while being vulnerable to the outside world for long periods of time?  The answer lies in different sleep schedules.

 Carnivores use a lot more energy and have few predators, so they are able to sleep for long periods of time.  Omnivores and herbivores have many predators so they sleep less.  Goes hand in hand with the Energy Conservation and Restorative (next) theories. Different Sleep Patterns

Restorative Theory  Non-Rapid Eye Movement (NREM) is extremely important for bodily growth and repair.  Rapid Eye Movement (REM) is important for the re-calibration of the brain and its information.  When we eat, our metabolism is at its highest; after we eat a large meal, we get sleepy, which is a natural response of the body to enter synthesis mode.  Several processes occur at a higher rate when we are asleep:  Increased cellular repair  Cellular growth  Mitosis- cellular division  Protein synthesis

Brain Plasticity – Learning  The Brain has the ability to change structurally and functionally in response to diverse internal or environmental factors.  During REM, the brain process the new information and integrates it into long-term memory.  Young individuals experience REM more often than adults – this is why they need more sleep.  It has been observed that young developing mammals experience depression-like symptoms when deprived of sleep.  Learning something new= more sleep required.

Sleep Issues…  What happens when we don’t get adequate amounts of sleep?  Too much sleep:  Weight gain and/or increased risk of obesity  Heart conditions  Changes in behavior.  Too little:  Tiredness, inability to function properly  Defensive behavior; “moodiness”  Decreased performance of nervous, digestive, and immune systems.  And so on.

What Does all This Mean?  Sleep is a complex phenomenon  There is no one correct answer; all of these theories overlap each other in many ways and help answer the question of why we need so much sleep.  Bottom-line: sleep is essential for the development, protection, and repair of our body and brain.  Sleeping enhances memory and learning – understanding, problem-solving, decision-making, etc.  Even though we have made significant progress in this area, we have merely scratched the surface on the issue of sleep. It is clear that there is much more to be learned within this field.