The Impact of Sleep on Mood, Emotions, and Mental Well-Being

The impact of sleep in our lives

Most of us spend one-third of our lives sleeping. By the age of 90, we will have spent a total of 30 years in our dreams. The nature of sleep has been the subject of worldwide studies for decades, conducted in the fields of neurology, psychology, anthropology, and sociology. But how does sleep impact our productivity? What is the optimal sleep cycle? How to deal with insomnia?

What Is Sleep?

According to, sleep is a natural state of mind and body, involving many physiological processes and characterized by lowered inhibitions, limited awareness of the surroundings, and altered brain activity. 

There are two basic stages of sleep: rapid eye movement sleep, or REM, and non-REM sleep. 

Non-REM sleep

occurs right after the transition from wakefulness to sleep.

It’s divided into four stages which last for about 90 minutes in total.

During non-REM, your breathing slows and evens out, with blood pressure lowering and muscles relaxing.

Your eye movements slow and then come to a stop.

Brain wave activity begins to slow from its normal patterns.

This stage allows you to rest, recuperate, and feel refreshed in the morning.

REM sleep

follows the non-REM stage.

REM sleep duration ranges from 10 to 20 minutes, and in that span of time your body temperature increases, followed by your heart rate and blood pressure.

Your body is temporarily paralyzed, with the exception of muscles responsible for respiration and pumping your heart.

Your eyes move rapidly behind closed eyelids, hence the name was given to this stage.

Brain activity is characterized by more rapid brain waves.

Most of your dreaming occurs during this stage.

Alternations between non-REM and REM sleep stages happen several times during the night.

All stages of non-REM sleep take place in a span of about 90 minutes.

Then the first short REM stage begins, lasting only around 5 minutes, and concluding one cycle.

Cycles are recurring, and each repetition shortens non-REM stages and prolongs REM stages up to 1 hour.

Healthy individuals usually go through five cycles of sleep on a normal night.

Sleep deprivation disrupts normal functions of several areas in the brain.

For instance, the slowing of neurotransmitter functions in the parietal lobe can inhibit reflex response, and dysfunction in the prefrontal cortex may lead to problems with verbal expression and eyesight.

Prolonged brain activity leads to mental fatigue and can cause a series of health problems.

The Effects of Sleep Deprivation on Your Body

Deterioration of the overall cognitive function.

This includes problems with memory and attention retaining skills, concentration, verbal expression, balance, etc. It can increase the risk of car accidents and workplace injuries. It’s estimated that drowsy driving is responsible for every fifth traffic collision.

Weakened immune system.

Research shows that lack of sleep triples the risk of developing a number of illnesses. During sleep, your system produces cytokines, a type of protein that creates your body’s immune response by targeting infection and inflammation. Without sufficient sleep, your system secretes fewer cytokines, thus crippling the immune response.

Weight gain.

Lack of sleep increases the production of ghrelin, commonly referred to as the “hunger hormone”. It stimulates appetite and leads to overeating since the overworked brain is in constant need of sustenance, with a preference for something fatty and high in carbs.

Performance loss.

When you lose sleep, it’s harder to be fast and efficient. Things that usually take an hour of your time suddenly become a three-hour-long affair. Your abilities to focus, process information and engage creatively start to suffer which reflects poorly on your performance.

Lack of motivation.

Chronic sleep deprivation can drastically reduce motivation to move towards achieving your goals and perform even the most basic of tasks. The longer you stay within this cycle, the harder it becomes to salvage what little motivation you have left.

Mood changes and addiction.

Regular lack of sleep often forces people to resort to various performance-enhancing substances like caffeine, nicotine, etc. Constant exhaustion can also affect your mood, make you irritable and quick-tempered. 


The effects of sleep deprivation take a serious toll on your appearance, especially your face and complexion. Little sleep usually means dark circles under your eyes, poor skin condition, and premature aging.

Circadian rhythms,

or your body’s biological clock, are internal functions regulating many physiological processes such as body temperature, metabolism, and the release of hormones.

Circadian rhythms determine our sleeping and waking hours based on environmental factors like light or temperature.

Optic nerves determine the amount of incoming light and transmit the information to the suprachiasmatic nuclei, or SCN, located in the hypothalamus.

This triggers the release of hormones—melatonin and cortisol—that play a huge part in controlling your sleep/wake cycle.


is a hormone produced at night by the pineal gland in your brain that determines when it’s time for you to sleep. It lowers blood pressure and body temperature, preparing your body for rest. Melatonin levels in the blood fall from their high night-time values with the start of the new day and remain very low during the daytime.

On the opposite end is cortisol,

which levels rise depending on the amount of light.

Cortisol is released in the morning when it’s time for you to wake up.

During the day, its values keep rising to sustain your energy levels.

So the light or lack, therefore, coordinate the roughly 24-hour cycle of our circadian rhythms, with melatonin putting us to sleep and cortisol waking us up.

But how much sleep do we need to be healthy and productive?

How to determine that one magic number of sleep hours during shorter summer nights or in artificial lighting environments that can alter the natural rhythms of your body?

Sharing is Caring. Thank you!