What Does Sleep Consist Of?

When to sleep, how to sleep, and how many hours? With so much to consider, it can be difficult to understand what’s required for the best quality slumber. While most attention is centred towards the number of hours you get, it’s just as important to consider how many sleep cycles you go through.

Each sleep cycle contains the same stages of sleep – REM, NREM, deep sleep – and it’s only by going through these that we can wake feeling refreshed. In this article, we’ll explore each of those sleep stages and how your biological makeup can define what type of rest you need.

What makes up our sleep?

While everyone needs a different amount of sleep, the recommended range is between 7 and 9 hours. This allows for your body to rest, recover and process information. But it doesn’t all happen at once. Instead, your body recovers differently as your brain goes through 2 main phases of sleep:

1. Rapid eye movement (REM):

During REM sleep, your eyes move rapidly despite the lack of visual cues. In this phase, you process emotions, memories and dreams. Learn more about what your brain goes through during this phase in our guide to REM sleep.

2. Non-rapid eye movement (NREM):

NREM is divided into smaller stages called N1, N2, and N3, which are initial, light, and deep sleep. The most important of these is deep sleep. It’s critical for restoration, healing, growth and consolidating what you’ve learned throughout the day.

It takes you about 90 minutes to go through these two phases. And for maximum impact, you want to go through about 4-6 of these cycles per night. Therefore, most people feel rested after 7-9 hours of sleep.

A lot of maths, right? Thankfully, we’ve created a nifty tool to calculate your optimum shut-eye and wake-up times so you start every day feeling refreshed. Click below to get calculating!

So, while those 90 minutes where we go through each phase are important to understand, we also need to be aware of how we group these cycles together. This is what’s meant when we refer to sleeping patterns.

Different sleeping patterns:

The majority of people follow what is called a monophasic sleep pattern. This simply means that you get all of your sleep in one single swoop. It’s most popular because humans typically have a diurnal circadian rhythm – the opposite of nocturnal – where we are awake during daylight and rest when it’s dark. What’s more, monophasic patterns make sense because we can get all the sleep we need to stay healthy in one go during the time when there is less light.

However, it wasn’t always this way. Monophasic patterns became more common around the time of the Industrial Revolution. With an increase in the length of working hours and the introduction of artificial lighting, it became both easier and more necessary to stay up late. Simply put, after a long day at the factory, it became important to maximise free time with family and loved ones after work and into the later evening.

Before this, a different type of sleep style was common. The Medieval practice of a “first sleep” centred around a short sleep during the first few hours of the night, followed by a few hours of work by candlelight before going back to bed.

Here’s a small quote from a study comparing the changes in sleeping patterns between pre and post-industrial Europeans:

As for preindustrial Europeans… awakening shortly before midnight or at a later hour was thought completely natural. What, of course, these cultures shared with early societies in Europe and, too, with the subjects of a well-known study conducted in the early 1990s at the National Institute of Mental Health by Dr. Thomas Wehr, was an absence of artificial illumination.

These older, non-monophasic cycles are often the focus of sleep researchers and anthropologists looking to uncover the most efficient way for humans to sleep. But you don’t need to look so far back to find examples of alternative sleep cycles. They’re still present in society today. The most common are what’s referred to as biphasic sleep – a set of two sleep sessions. Typically, these include one long sleep and one short, somewhat similar to the Medieval first and second sleep.

For example, think of countries where the siesta still reigns supreme. This afternoon nap is popular in warmer countries, where industry shuts down in line with rising temperatures, is a perfect example of a biphasic sleeping pattern.

Somewhat surprisingly, there are even more granular sleep patterns too. These fractured patterns consist of three or more sleep sessions per 24 hours. They’re known as polyphasic sleep.

Here are some of the most popular and how they work over 24 hours:

Everyman cycle: 4 hours of total sleep split into one 3-hour block and three 20-minute naps
Dymaxion cycle: 2 hours of total sleep split into four 30-minute naps
Uberman cycle: 2-3 hours of total sleep split into six to eight 20-minute naps

As you can see, these patterns are pretty extreme and aren’t really designed for long-term use. There’s a lot of research that shows polyphasic ultra-short sleep has adverse effects. Very short sleep periods can often lead to sleep deprivation, which has serious negative impacts, including increased risk of cardiovascular disease, diabetes, and depression. Here’s a quote from a study on ScienceDirect.com on the matter:

Based on the current evidence, the consensus opinion is that polyphasic sleep schedules, and the sleep deficiency inherent in those schedules, are associated with a variety of adverse physical health, mental health, and performance outcomes. Striving to adopt a schedule that significantly reduces the amount of sleep per 24 hours and/or fragments sleep into multiple episodes throughout the 24-hour day is not recommended.

For those with unusual working patterns like night shifts, you may be forced into splitting your sleep up to fit your schedule. If that is the case, we advise speaking to your GP about the healthiest approach.

It’s not only the phases of sleep and the patterns in which we group those phases which are important for optimising sleep. It’s equally important to understand how our genetics and sleep preferences affect the quality of our rest. Most important for this is understanding your sleep chronotype.

Should our sleep cycles be influenced by our chronotypes?

We’re all familiar with the saying that some people are night owls and others early birds, but is there some scientific truth to this?

Yes! Chronotypes have been studied by scientists to better understand how they work and why. At it’s most simple, your chronotype refers to when you are most alert and when you’re most likely to fall asleep.

There is variation, typically around 2-3 hours, but generally speaking, evening types will get sleepy in the very early morning and sleep through until the late morning. Morning types will rise more in line with sunrise. So, if you’ve always struggled with the cultural norm of working 9-5, it may have something to do with your biology!

Clearly, there’s a link to sleep patterns here too. Understanding when you are both most and least alert is key to finding a sleep routine that works.

For example, if you’re a morning person, you’re probably best set for a monophasic sleep pattern. One where you can rise with the sun and work through the day.

For night owls who stay up late, an afternoon siesta may be the ticket to improving energy levels and maximising focus – particularly if your employment requires an early start!

Consider the following 6 distinct types and which is most like yourself:

Morning type: Energy levels are highest in the morning and wane through the day
Daytime type: Energy starts low and peaks at midday before dropping again
Evening type: Energy starts low and increases into the evening and night
Moderately active type: Energy levels are constant through the morning to evening but never have a high peak
Highly active type: Energy levels are constantly higher than average no matter what time
Daytime sleepy type: Energy starts high and drops dramatically during the middle of the day, rising again in the evening