The Science of Sleep – What Is It and Why Do We Need It?

Until the 1950’s people thought sleep was just a passive, dormant part of our lives. However, we now know that our brains are hugely active during the time we are asleep. Sleep, along with nutrition and exercise, is one of the most important things we can do to ensure we have a healthy life.

Most people recognise sleep as a period in our lives when we lay down and go into a state of unconsciousness; we suspend our normal activities and then wake up hours later to begin our daily routine all over again. Actually, sleeping helps our bodies to recuperate and go through a period of restoration required for us to function normally the next day.

Margaret Thatcher was famously said to survive on only four hours of sleep a night. But what happens to the human body if we don’t sleep for long enough?

After just one night without sleep, and you’ll know this if you’ve ever pulled an all-nighter, it becomes immensely difficult to concentrate, you’ll feel grumpy, groggy, irritable and forgetful. With a continued lack of sleep, the part of the brain that controls language, memory, planning and even sense of time practically shuts down as it’s that severely affected.

One famous experiment in 1959 saw a DJ, Peter Tripp, stay awake for eight days. After 100 hours he was unable to perform simple maths problems and couldn’t recall the alphabet. After 120 hours, he started to hallucinate.

In a study by Washington State and Pennsylvania Universities, they studied 48 healthy men and women; all of whom slept for around seven to eight hours a night. They divided them into four groups:

• The first group had to stay awake for three days without sleeping
• The second group slept continuously for four hours a night
• The third for six
• The fourth for eight

After 14-days, the fourth group who slept for longest showed no cognitive decrease but the others did. In fact, the second group who slept for four hours a night performed the worst of them all. Frighteningly, the participants didn’t even realise they were declining. They believed their mental state got worse for a few days but then tapered off when in reality they were getting worse and worse each day.

Non-REM Sleep

The first stage of our sleep is non-REM and it goes like this:

Stage 1 - Light Sleep

During this stage, we’re half asleep yet half awake. You’ll find that in this period of sleep you can be awoken easily. Your muscle activity slows down and you may twitch involuntarily.

Stage 2 - True Sleep

Within around ten minutes of light sleep, you enter stage two. This usually lasts a further 20 minutes where breathing and heart rate start to slow right down.

Stages 3 and 4 - Deep Sleep

This is when the brain starts to produce delta waves. These are associated with the deepest levels of sleep, relaxation, and peace of mind. Delta waves allow the person to wake up feeling refreshed; they allow the body to heal itself, improve the immune system, regulate body functions and actually, can help a person to be more empathetic and intuitive. Stage 3 is when our breathing and heart rate are at their lowest levels.

Delta sleep is when sleepwalking and sleep talking are most likely to occur. It’s also the most common time where children may experience bedwetting and night terrors. Stages three and four are the stages of sleep where it’s very difficult to wake someone; with very little muscle activity and no eye movements present.

REM Sleep

The rapid-eye movement (REM) period of sleep usually begins around 90 minutes after someone first falls asleep and reoccurs after every 90 minutes. We generally have around three to five cycles of REM sleep a night. Named REM sleep because our closed eyes move rapidly side-to-side during this time, breathing becomes shallow, heart rate increases, blood pressure rises and your muscles are temporarily paralysed. Interestingly enough, when a person is in REM sleep the brain waves look a lot like those recorded when someone is fully awake.

There’s no universal definition for how long you have to be without sleep to be ‘sleep deprived’ however research has suggested that, over time, people show physical and psychological damage from not having enough sleep.

Firstly, in low levels of sleep deprivation a person’s cognitive and emotional function will be impaired. For example, a person who is sleep deprived may not recognise the emotions of others as easily, mistaking a positive look for a neutral one and a neutral look for a negative one. Additionally, a person may experience 'microsleeps’ where, although their eyes are open, their brain goes into a sleep state rapidly and uncontrollably for around 30 seconds at a time. This means they are effectively blind and can be extremely dangerous whilst driving.

Lack of sleep can seriously affect health in the long term too. It can make a person more susceptible to obesity, high blood pressure, diabetes and heart disease. In fact, sleep seems to be the most important indicator of how long you’ll live.

When a person is suffering from lack of sleep, or ‘sleep debt’ as it’s known, their short-term memory is affected and what they have learned during the day, may not have ‘filed’ during the night.

We also lose our capacity to create, plan and carry out activities. Those suffering from sleep debt have found to have decreased levels of humour, social skills and ability to concentrate. We’ve all encountered at least one instance where we’ve felt irritable, depressed and anxious whilst tired and this can also indicate you’re in sleep debt.

But what about the physical effects of sleep debt? Well, we find it harder to metabolise free radicals. Free radicals are molecules that are said to affect the aging cells and can even cause cancer. We’re more susceptible to colds and flu as our immune functions are affected. People suffering from sleep deprivation may notice an increased sensitivity to pain and, even, a lower threshold for seizures.

Long-term, a lack of sleep can adversely impact our metabolism as our brain interprets a lack of sleep as a lack of food, can put us at greater risk of diabetes, weight gain, heart disease, and strokes so it really is essential that we promote sleep within the hospitality industry.

Impact on sleep and athletic performance were tested on Stanford basketball players. Given a goal to sleep for 10 hours a day, their athletic performance was then monitored. By the end of the extra sleep period, players had significantly improved in shooting and each one was quicker than before the study had started.

Experts say 95% of people need seven to nine hours of sleep a day to function optimally – or rather people who sleep for less than 7 hours will experience decreased mental and physical performance.

In the 1960’s, at the height of the ‘Space Race’, Michael Siffre decided to spend time in isolation, in caves. In the first experiment, he spent 63 days in the cave and although his mind had lost track of time, his body had not as he had maintained a regular sleep schedule amounting to around a 24.5 hour day.

He had kept regular cycles of sleeping and waking unintentionally which proves humans have internal clocks.

We mentioned Margaret Thatcher earlier, so how long do other people in our history sleep for?

• Margaret Thatcher was said to get 4 hours of sleep a night.
• Donald Trump has said he sleeps 3-4 hours a night according to his book.
• Leonardo Da Vinci apparently used the Uberman Sleep Cycle and had a 20-minute nap every four hours meaning he only slept for 2 hours on average a night.
• Mariah Carey claims she needs 15 hours of sleep a night.
• Albert Einstein was said to sleep for 10 hours a night.

So, what do you need for a really great night’s sleep?