Four variables for perfectly restful sleep
When people talk about getting the perfect amount of sleep, they tend to focus almost exclusively on the amount of sleep. Although total sleep time is an important consideration, it is not the only one. In the same way, we should care about its quality.
When it comes to quality restful sleep, you need to look at four variables that affect it. In addition to the length of sleep, its quality, time to sleep and consistency also come into play. Let's look at all the factors now.
Quality of sleep
Quality is as important as quantity. Have you ever slept for 9 hours and woken up in the morning feeling like you didn't get any rest at all?
The number one key to long-term quality sleep is regularity. The sleep-wake cycle plays an important role in controlling our circadian rhythm. Going to bed and getting up at the same time is an incredibly powerful aid to quality sleep. A regular sleep schedule can optimize our circadian rhythm, which then takes care of sleep-related processes in the body more effectively. Timely and more efficient release of hormones, control of body temperature and other processes will ensure better quality and more restful sleep.
Related: Stages of sleep - do you know what happens to our body during them?
Quantity
There is no single number that tells us how many hours of sleep we need. The generally recommended 7-9 hours applies to a large part of the adult population, but your particular chronotype genetically predisposes you to a certain amount of hours that the body needs. There is no universal advice, however, it turns out that less than 6 hours of sleep significantly accelerates physical and mental exhaustion. Time to physical exhaustion (stamina) can drop by up to thirty percent. [ From the book Why We Sleep] So if you want to use your mental and physical potential to the maximum, make sure you get at least 7 hours of sleep. 
Time to sleep (latency)
Time to sleep is a very important indicator. Usually falling asleep should not take more than 15-20 minutes. If the time to fall asleep exceeds this time, it may indicate a thrown circadian rhythm. In that case, it is advisable to think about and adjust your bedtime routine, which will limit excessive stimulation of the organism. Eliminate work, looking at screens, social networks and heavy meals. Some people are very sensitive to falling asleep, which is why it can be absolutely crucial for them to have a regular and strict sleep schedule. Otherwise, the organism does not know when it is time to sleep and the body cannot prepare for it in time.
If, on the other hand, you fall asleep in less than 5 minutes, it may be a sign that you went to bed too late or you have an insufficient amount of sleep for the body's needs. This can mean two things. Either you had an incredibly physically demanding day, or your body needs more sleep than you are giving it.
Consistency of sleep
One of the variables that can affect the quality of sleep is its continuity. The more restful sleep you have without unnecessary movement at night, the more REM and deep sleep you will have. This means that more consistent sleepers not only sleep more, but have more restorative and more efficient sleep than people who sleep for a similar amount of time but with inconsistent sleep.
