Why Do We Sleep? What Happens During Sleep?

What Is the Purpose of Sleep?

Sleep gives your body, including your brain, time to repair itself and carry out important functions, like clearing out waste and releasing hormones.



Sleep is essential for good health. In fact, we need sleep to survive — just like we need food and water. So, it’s no wonder we spend about one-third  of our lives sleeping.

Many biological processes happen during sleep:



• The brain stores new information and gets rid of toxic waste.

• Nerve cells communicate and reorganize, which supports healthy brain function.

• The body repairs cells, restores energy, and releases molecules like hormones and proteins.

These processes are critical for our overall health. Without them, our bodies can’t function correctly.

Why do we sleep?

• A lot is still unknown about the purpose of sleep.
 
• There isn’t just one explanation for why we need to sleep.

• It’s likely necessary for many biological reasons

Advantage of sleeping 💤 :




• Energy conservation

• Cellular restoration(muscle repair, Protein synthesis, Tissue growth, Hormone release) 

• Brain function(Learning, Memory, Problem-solving skills, Creativity, Decision making, Focus, Concentration)

• Necessary for emotional health.

• Weight maintenance

• Proper insulin function. 

• Immunity.

What happens when you sleep?

Your body cycles through four stages of sleep. This cycle occurs multiple times throughout the night for different lengths of time, varying from 70 to 120 minutes each. The stages generally repeat about four to five times during a 7- to 9-hour sleep period.

Two major phases of sleep:

• Non-REM (non-rapid eye movement)  sleep - 3 stage. 

• REM (rapid eye movement) sleep. 


The four stages of sleep are listed below.

Stage 1: Non-REM sleep

Stage 1 occurs when you first fall asleep. As your body enters light sleep, your brain waves, heart rate, and eye movements slow down.

This phase lasts for about 7 minutes.



Stage 2: Non-REM sleep

This stage involves the light sleep just before deep sleep.

Your body temperature decreases, your eye movements stop, and your heart rate and muscles continue to relax. Your brain waves briefly spike then slow down.

During a night of sleep, you spend the most time in stage 2.

Stage 3: Non-REM sleep

In stages 3 and 4, deep sleep begins. Your eyes and muscles don’t move, and your brain waves slow down even further.

Deep sleep is restorative. Your body replenishes its energy and repairs cells, tissues, and muscles. You need this phase to feel awake and refreshed the next day.

Stage 4: REM sleep



This stage first happens about 90 minutes after you fall asleep. Your eyes move quickly from side to side during REM sleep.

In REM sleep, your brain waves and eye movements increase. Your heart rate and breathing also speed up.

Dreaming often happens during REM sleep. Your brain also processes information during this stage, making it important for learning and memory


How much sleep do you need? (the following durations ) 


Birth to 3 months: 14 to 17 hours
4 to 12 months: 12 to 16 hours per 24 hours, including naps
1 to 2 years: 11 to 14 hours per 24 hours, including naps
3 to 5 years: 10 to 13 hours per 24 hours, including naps
6 to 12 years: 9 to 12 hours
13 to 18 years: 8 to 10 hours
18 to 60 years: 7 or more hours
61 to 64 years: 7 to 9 hours
65 years and older: 7 to 8 hours

What happens if you don’t get enough sleep?



• Anxiety
• Depression
• Poor memory
• Poor focus and concentration
• Poor motor function
• Weakened immune system
• Weight gain
• High blood pressure
• Insulin resistance
• chronic diseases like diabetes and heart disease
• Increased risk of early death.