During sleep, your body goes through a series of changes that allow for rest that is important for overall health. Your body and brain have time to recover, allowing for better physical and mental performance the next day.

Sleep and regular sleep-wake cycles play an important role in controlling the development of various hormones. Getting enough deep sleep is essential for maximizing potential gains from strength training and regenerating cells to repair tissue and bone and stimulating blood flow to muscles for recovery. 95% of growth hormone is produced during deep sleep.

The National Sleep Foundation recommends 8–10 h for teenagers (aged 14–17), 7–9 h for adults (18–64), and 7–8 h for older adults (≥65). Consensus evaluations of more than a thousand scientific articles have yielded that the sweet spot for most people is ideally somewhere between 7 and 7 and a half hours.

When getting less than 6 hours of sleep, studies show a significant increase in mortality and health outcomes such as diabetes, cardiovascular disease, coronary heart disease, and obesity.

On the flip side, sleep duration over 9 hours has been correlated with more significant mortality and increased mortality, diabetes mellitus, cardiovascular disease, stroke, coronary heart disease, and obesity.

Bottom Line: A lack of sleep is a significant risk factor for poor health and should be avoided at all costs.

As we go about our day, we constantly experience and adapt to the world around us, learning and growing. Our experiences continually shape our worldview, and our brain is continuously changing as a result. New events become electrical impulses that spread through the hippocampus's neural networks, an area of the brain responsible for the formation of new memories. These impulses, or new memories, change synaptic connections, making some more potent and some weaker. 

For something to become a memory, three functions must occur.

1. Acquisition - learning or experiencing something new

2. Consolidation - the memory becomes stable in the brain

3. Recall - having the ability to access the memory in the future

With everything comes balance, and neuroplasticity is no different. The brain needs time to integrate and sort things out, which is where sleep comes in. 

It is unsustainable for the neurons to keep firing throughout the day without down-regulating. When we go to sleep, the processing occurs, and the important memories are consolidated into existing networks and transferred to the cortex for more permanent safekeeping.

During deep non-REM sleep, neurons oscillate between a depolarized on-state when they fire and a hyperpolarized off-state when they are silent. A recent study demonstrated that dueling brain waves called delta and slow-oscillation essentially serve two different functions during this down-regulation. Delta waves inhibit memory formation, while slow-oscillation waves do the encoding.

A recent study indicated that it is possible to enhance language learning during slow-oscillation wave periods. The study demonstrated that word associations are registered and encoded at the peak of these slow-oscillation waves. On the flip side, science has proven that in brains that show a buildup of amyloid plaques, a hallmark of Alzheimer's disease, delta waves proliferate.

When awake, learning occurs. When asleep, sorting and processing occurs based on relevance and future expectations of usefulness so that the essential memories are easier to retrieve for future use.

Without adequate sleep, the brain has a more challenging time absorbing and recalling new information. Studies show that better quality, longer duration, and greater sleep consistency are strongly associated with better academic performance.

Dreams occur most frequently during REM sleep but can occur during any stage of sleep. However, dreams that occur during non-REM and REM sleep seem to show different patterns. 

REM dreams tend to be more imaginative, immersive, and nonsensical, enhancing the integration of unassociated information for creative problem-solving. 

While dreaming, this fluid interpretation is at the core of a creative mind, working without rules to create and imagine the unimaginable. Many ideas and inspirations originate during dreamtime and are responsible for some of the world's greatest inventions and discoveries.

In 1619, a young soldier stationed in Germany had three dreams involving spirits, including an evil spirit and the holy spirit. That soldier was Rene Descartes, and those dreams gave rise to dualism.

In 1845, Elias Howe invented the sewing machine. He had been contemplating the idea of a device with a needle that would go through a cloth and had a dream that helped provide some newfound inspiration. In the dream, Elias found himself surrounded by cannibals about to be cooked and eaten. While observing them dance around a fire with spears moving up and down, he noticed a hole at the tops. Upon awakening, he realized that having a hole in the needle close to the point, instead of the other end, provided the solution he had been looking for, making the mechanical sewing machine a technological possibility.

In 1953, a young molecular biologist had a dream involving a spiral. That spiral ended up becoming an inspiration for the discovery of the double-helix structure of DNA. Imagination and creativity are interwoven, and human progress directly correlates with both.