The exact reason why we sleep remains one of the most enduring and intriguing mysteries in health science. To try to get to the bottom of this question, experts analyze how sleep works and what happens when we don’t get enough sleep. This knowledge reveals how sleep is connected to numerous elements of physical, emotional, and mental health and how people can get better sleep.
What Happens When You Sleep?
Within a minute after falling asleep, notable changes start to affect both the brain and body. Body temperature drops, brain activity ramps up, and heart rate and respiration slow.
- Over the course of one night, you actually progress through multiple sleep cycles, lasting between 70 and 120 minutes.
What Chemicals and Hormones Regulate Sleep?
Shifting between wakefulness and sleep creates changes in thousands of neurons in the brain and a complex signaling system that generates specific reactions in the body.
- Neurotransmitters are chemicals that send signals within the nervous system to activate or deactivate certain cells. Examples of neurotransmitters involved in promoting wakefulness or sleep include GABA, acetylcholine, orexin, and serotonin.
Why Is Sleep Important?
Numerous indicators support the view that it serves an essential biological function
- The fact that sleep exists in almost all animal species is a strong indication that it is fundamental to well-being
- In humans, sleep appears to be critical to both physical and mental development
- A lack of sleep has been associated with a wide range of negative health consequences including cardiovascular problems, weakened immune system, impaired thinking and memory, and mental health problems
What Are the Sleep Stages?
There are four stages of sleep divided into two categories: non-REM (rapid eye movement) sleep, stage 3, Slow-Wave Sleep (SWS), Delta Sleep, Deep Sleep, and Deep Sleep 20-40 minutes.
- Stage 3 is the deepest part of NREM sleep. In this stage, your muscles and body relax even more, and brain waves show a clear pattern of slowed activity that is markedly different from waking brain activity.
How Does the Body Regulate Sleep?
The body regulates sleep with two key drivers: sleep-wake homeostasis and the circadian alerting system: these factors directly affect how much your body feels a need for sleep, reflecting your biological clock, the time of day, your light exposure, and how long you’ve been awake.
