Do Humans Really Need To Sleep 8 Hours a Day?

The length and quality of deep sleep affect how rested we are. Hence, it is worth taking a look at all the important factors in promoting deep sleep. 

Sleep is a vital and indispensable part of our lives. It is necessary for the regeneration of the body, for the systematization and processing of new knowledge learned during the day. 

Emotional effects during waking are also partially in place during sleep. In the absence of adequate quantity and quality of sleep, we will be tired and sleepy.

Scientific research makes clear that sleep is essential at any age. Sleep powers the mind restores the body and fortifies virtually every system in the body. But how much sleep do we really need in order to get these benefits?

National Sleep Foundation guidelines advise that healthy adults need between 7 and 9 hours of sleep per night. Babies, young children, and teens need even more sleep to enable their growth and development. People over 65 should also get 7 to 8 hours per night.

Knowing the general recommendations for how much sleep you need is the first step. Then It’s important to reflect on your individual needs based on factors like your activity level and overall health.

Finally, of course, it’s necessary to apply healthy sleep tips so that you can actually get the full night’s sleep that’s recommended.

The night sleep phases

Nocturnal sleep consists of 90-120-minute sleep cycles that alternate 4-6 times during the night Within sleep, we separate the REM and non-REM sleep phases. 

(REM is an English abbreviation for rapid eye movement.) The non-REM phase is divided into three additional sleep phases. 

Let’s see these sleep phases!

Stage 1: nap

The initial stage of sleep is during which the body prepares to sleep. It lasts only a few minutes, accounting for 5-10% of sleep time. 

Key features:

• slowing of body functions during sleep (eg heartbeat, breathing, eye movement), 
• slowing down brain waves (however, alpha waves are also typical),
• decreasing muscle tone. 

Stage 2: superficial sleep

This stage makes up about half of the sleep time. During sleep, life functions and brain waves slow down further (theta waves are typical), and muscles relax even more. Eye movement stops completely and body temperature drops. 

Stage 3: Deep sleep

This sleep phase is referred to in the literature as the delta phase because brain waves slow down further and are often divided into two phases. 

The first is medium-deep sleep, which accounts for 5-10% of sleep, and the second is deep sleep, which accounts for 15-20% of sleep time. 

In addition to extremely slow brain waves, this phase is characterized by decreasing blood pressure and slow breathing. 

Otherwise, it is much harder to wake someone up, even with loud noises, it is difficult for the sleeping person to react. 

However, if you manage to get up in this phase, you will typically be very “comatose”, confused, dizzy and hard to recover. 

Stage 4: dream sleep, i.e. REM sleep

This phase accounts for roughly 20% of sleep time and is sharply separated from the rest of the sleep stages. The eyes begin to move rapidly while experiencing the following characteristics during sleep:

• breathing becomes faster, more irregular and superficial,
• muscle tone ceases, limb muscles block,
• cerebral blood flow becomes more intense, almost doubling,
• brain activity is similar to alert and dormant states.

At this stage, we dream while the brain areas responsible for learning, thinking, and organizing work are particularly active. According to experts, the brain also processes and selects new information collected during the day. 

Interestingly, the order of the sleep phases is always the same within one cycle: 1-2-3-2-1-4, and then the next cycle begins. This is so true that if someone e.g. awakened in phase 3, he goes through phases 2-1-4 with lightning speed before recovering

Do we dream during deep sleep?

So perhaps the two most important stages of sleep are deep sleep and REM sleep. Even today, the misconception that we dream in deep sleep often arises. Yet, as already mentioned, dreams are specifically characteristic of REM sleep. 

The functioning of the brain can also be likened to a computer that receives a lot of information through the senses during the day. 

Only a fraction of these reach our consciousness, much of it is stored in the unconscious. At night, in the REM phase, this information stored in the unconscious is systematized. Logical information, numbers are placed in the appropriate “store”, as are emotionally accentuated events in another, and so on. Unnecessary information is permanently deleted. 

According to the current state of science, this process actually takes place during REM sleep, and dreams are the “by-products” of this. So the answer to the question in the subtitle is: We dream during REM sleep, not during deep sleep. 

Its significance 

It is of paramount importance to rest to sleep soundly. During this phase, a number of processes take place that contributes to the regeneration of the body and plays a key role in relaxation:

• the body to rest the day before,
• the cells regenerate, the energy level of the body is restored,
• the process of glucose processing is then most intense in the brain,
• growth hormones are released, which also contribute to tissue renewal.

As already mentioned, the different sleep phases form sleep cycles, 4-6 of which follow each other during the night. At the beginning of sleep, the first phase of deep sleep is usually 45 to 90 minutes. As the night passes, the deep sleep phases shorten as the REM sleep phases become longer. 

However, to the question of how much sleep is needed to fully rest oneself, it is not easy to give an accurate answer. 8 hours of sleep a day is now considered too common. 

Some adults are also perfectly fit with 4-5 hours of sleep, others need 9-10 hours. The need for sleep is also affected by the physical and health condition of the body. 

Therefore, according to the current state of science, it is not really possible to determine a specific number of minimum amounts of sleep. Instead, everyone should try to sleep enough to make them feel rested the next day. 

Secret of deep sleep

In order to wake up relaxed, it is worth doing everything to make the phase of deep sleep as harmonious as possible. 

Here are some good tips:

• Sleep is aided by the low temperature in the room – around 20 degrees. However, before going to bed, a sauna or a hot bath is especially good for deep sleep. 
• It’s a good idea to set up a bedtime ritual: it’s good to have a proven choreography for this. For example, two hours before going to bed, we only use low-intensity light sources, we avoid staring at screens, we always drink our evening – strictly decaffeinated – tea at the same time, and so on.