1)

• the structure of a person's sleep stages and cycles is known as their "sleep architecture".

2)

• stress
• hunger
• caffeine intake
• excessive use of electronic devices
• hormone melatonin

3)

• lack of sleep can lead to serious medical conditions; shorten your life expectancy
• sleep is paramount to the brain's ability to reorganize itself; fundamentally to well-being
• important for our physical and mental development
• lack of sleep can bring about cardiovascular and mental problems, like depression and anxiety
• lack of sleep can weaken immune system, increase the risk of obesity and diabetes