For high-powered leaders and CEOs, the ability to function on four hours sleep per night was a badge for honor.
Margaret Thatcher was notoriously uneasy about her sleep habits. Donald Trump boasted once that sometimes he only slept three hours.
A wealth of recent scientific studies have shown that not enough sleep can result in a number of potentially life-threatening conditions.
However, two thirds of all adults in developed countries fail to sleep for the eight hours recommended.
There is a tiny subset of the population — about one in 4million of us — born with a gene that allows them to thrive on half of that amount.
For the majority of people, however, sleeping for less than 6 or 7 hours per night will severely degrade your immune system. This can increase your chances of getting many types of cancer.
Even moderate reductions in sleep for just a week can disrupt blood sugar so profoundly you would be classified as pre-diabetic.
Sleep deprivation also increases the risk of your coronary arteries becoming blocked and brittle, setting you on a path towards cardiovascular disease, stroke or heart failure.
Perhaps you have noticed you crave junk food when you’re tired? Too little sleep swells concentrations of a hormone that makes you feel hungry, while suppressing a companion hormone that signals food satisfaction.
Routinely sleeping less than six or seven hours a night demolishes your immune system and significantly raises your risk of developing numerous forms of cancer. A slight reduction in your sleep time for as little as a week could cause blood sugar to drop so severely that you’d be considered pre-diabetic. Your risk of having your coronary vessels become blocked or brittle from short sleeping can also increase, putting you at high risk of developing heart disease, stroke and cardiovascular disease. Perhaps you have noticed you crave junk food when you’re tired? Lack of sleep can increase your appetite and suppress your companion hormone, which signals hunger.
Sleep also seems to be a key lifestyle factor that determines whether or not you will develop Alzheimer’s disease — with getting too much or not enough both linked to the disease.
It can also lead to anxiety and depression. This has been shown to be linked with suicide.
So, how do you know whether you’re routinely getting enough sleep? One good rule is to check if it’s possible for you to fall asleep between 10 and 11 a.m. If you answered yes to this question, then your sleep is probably too short.
A study of 60,000 middle-aged and elderly Britons, published this week, found those who regularly need to nap during the day were 12 per cent more likely to develop high blood pressure than their peers.
Researchers concluded that naps were not the cause of the problem and instead suggested that they could be a sign of low quality sleep.
Cancer
Insufficient sleep is linked to increased ‘wear’ and tear on cells. Cancerous tumours can be caused by this type of genetic disruption.
According to a 2019 study, people working night shifts are 30% more likely to have DNA damage than those who work regular hours.
University of Hong Kong researchers examined around 50 local doctors. The majority of these people had to work night shifts and got only two to four hours of rest. Rest got seven hours or more.
Ohio researchers found that those who sleep less than 6 hours per night are at 50% higher risk for developing bowel cancer.
With this type of cancer being the second deadliest in the UK and US, the Case Western Reserve University study concluded that short sleep is a ‘public health hazard’.
Lack of sleep can cause DNA damage and suppress levels key hormones.
It is the key to our feeling tired. Although levels of this hormone are low throughout the day, they increase as time goes by and you start to feel tired.
The lack of sleep or fragmentation can cause melatonin to be reduced.
Lack of sleep could indirectly increase the risk of developing cancer by making you hungrier or fatter.
In 2012, research published in the journal PLoS One looked at the cancer risk in nearly 25,000 middle-aged adults across Europe.
It found people who slept less than six hours per night were 43 per cent more likely to develop cancer in their lifetime than those who got seven or more hours.
Another 2019 study showed that patients who slept for less than six hours each night were three times more likely (in the 30-year time frame) to develop cancer.
Penn State University’s researchers examined 1,654 individuals aged between 20 and 74 with history of stroke or heart disease.
The Journal of the American Heart Association published a study that found people who are sleep deficient had a 2.92-fold higher risk of developing any form of cancer in the following 30 years than those who get enough rest.
Heart disease
The link between an unhealthy sleeping pattern and an unhealthy heart is becoming undeniable.
The impact of inadequate sleep on the cardiovascular system increases as we reach midlife.
The risk of having a stroke or heart attack in an adult aged 45 years or older is 200 percent higher for those who sleep six to seven hours each night, as opposed to adults who get up to eight hours.
This finding, from a 2012 study by Chicago University, emphasises how important it is to prioritise sleep in midlife — which is unfortunately the time when family and professional circumstances encourage us to do the exact opposite.
It doesn’t take much sleep deprivation to impact your cardiovascular system. One night of modest sleep reduction — even just one or two hours — will promptly speed the contracting rate of a person’s heart, hour upon hour.
It also leads to a substantial increase in systolic Blood Pressure, which places greater stress on the heart.
It is not possible to find comfort in knowing that all the studies that supported this conclusion were done in healthy, young people who had a normal cardiovascular system.
Lack of sleep not only increases your heartbeat and raises your blood pressure, but it also damages your blood vessels.
Particularly affected are the blood vessels that supply the heart with oxygen. You must keep these open and clean at all costs.
If these passageways are narrowed or blocked, your heart can suffer a comprehensive — and often fatal — attack caused by blood oxygen starvation.
Donald Trump is known for sleeping as little at three hours per night. But, it’s rumoured that Trump napped during the day to compensate.
Atherosclerosis is one cause of coronary artery obstruction. This occurs when calcium deposits and hardened plaques build up within the arteries.
There is also a yearly ‘global experiment’ that involves 1.5 billion people and highlights the link between a poor night of sleep and our heart health.
Most people lose an hour sleep in the Northern Hemisphere when daylight savings time is switched to March.
Researchers have examined millions of hospital records, and found that a seemingly innocuous reduction in sleep is associated with an alarming increase in the risk of heart attack within 24 hours.
You can use it both ways. It works both ways. In autumn, heart attack rates plummet after the clocks turn back an hour, which is when the clocks stop.
Similar rise-and-fall relationships can also be observed with suicide rates and traffic accidents.
The brain is as susceptible to small disturbances in sleep as the heart, thanks to microsleeps, attention lapses, and emotional instability.
Dementia
There is increasing evidence that a lack of sleep during middle-age can cause dementia later on in life.
According to some studies, if you don’t get enough sleep, your brain doesn’t have the chance to eliminate beta amyloid or other plaques.
The substances can continue to build up day by day until they become a memory-robbing condition.
An analysis of over 8,000 Britons between 50 and 70 found that those with less than 6 hours of sleep per night during middle-age were at 30% higher risk for developing late-onset dementia.
Cambridge University conducted separate tests in 2021 to determine if people who sleep less or more than seven hours a night were worse at thinking speed and attention span.
The researchers examined data from 498,277 adults aged 38 to 73, gathered from the UK Biobank — a database of patients monitored for 10 years.
Researchers at Stanford University produced similar results in their study of Americans 65-85 years old. This was published in August.
People with dementia often have trouble sleeping, so it is not clear if the sleepless nights are the cause of the problem.
Obesity
Short sleep duration may lead to obesity through an increase of appetite via hormonal changes caused by sleep deprivation.
Ghrelin (a hormone that, among other things, stimulates hunger) is produced by sleep deprivation.
Also, sleep deprivation can be associated with high cortisol and growth hormone deficiencies. Both of these have been shown to increase the risk of obesity.
A lack of sleep may also affect your metabolism.
A 2006 study of 75,000 children and adults by the University of Warwick’s Medical School found those who sleep less have a greater increase in body mass and waist circumference over time.
Short sleepers were twice as likely to be overweight or obese at all ages. A short sleeper is someone who gets less sleep than their reference age group.
A recent study found that those who were exposed to light at night had a 80% higher chance of becoming obese than those who were asleep in complete darkness.
Northwestern University researchers studied 552 individuals between the ages 63-84. The quality and quantity of your sleep can be affected by having lamps on at night. This is because it disrupts the body’s natural circadian rhythms, melatonin production, and can cause disruptions to the body’s natural circadian rhythms.
The pineal gland starts producing melatonin when it is dark. Light causes this production to cease. Sleep also reforms the body’s metabolic state by fine-tuning the balance of insulin and circulating glucose.
You must also maintain a healthy microbiome in your stomach, which is where most of our nutrition starts.
Inhibited immunity
This has happened to everyone. It happens when you aren’t getting enough sleep, and suddenly, your body gets a severe cold.
It isn’t a coincidence.
The immune system’s armoury is replenished by sleep, which helps to combat malignancy and prevent infection.
The immune system activates the sleep system when you fall ill. It demands that more people get enough rest to strengthen the war effort.
If you don’t get enough sleep, your immune system is robbed.
It has been proven that sleep deprivation can reduce the production of T-cells and antibodies, both vital in fighting infection.
Researchers at University of Tuebingen, Germany, compared the T cells of volunteers who were allowed sleep for 8 hours or who stayed awake throughout the night.
Researchers found that the levels of the key molecule involved in immune responses were lower in those who had not slept.
A separate study found levels of a key immune cell called a ‘natural killer’ cell were reduced by more than 70 per cent in people who don’t get enough sleep.
Even more research has shown that people who are not well-rested have a lower chance of receiving a complete immune response to vaccines.
Scientists discovered that adults immunized against influenza had antibodies half as high as their healthy peers in 2002.
Research also showed that those who slept less than 6 hours per night were, on average., much less likely to develop an antibody reaction to the hepatitis B jab.
The 2012 study found that they were 12 times more likely not to have the vaccine protect them than people who sleep more than seven hours.
Sex drive with low sex
It may not surprise the wives of long-suffering workaholic husbands.
Men who don’t get enough sleep may have a harder time getting their sex needs met.
A study by the University of Chicago in 2011 found those who sleep for less than five hours a night for periods of longer than a week have significantly lower levels of testosterone than those who get a full night’s rest.
Due to testosterone’s effects on men’s energy and libido, people who don’t get enough sleep will be more inclined to avoid sex.
According to the Journal of the American Medical Association, the effect is so severe that it lowers the levels of the hormone.
Another study in the Journal of Clinical Sleep Medicine found a third of men with sleep apnoea also experience lower testosterone levels.
Young, healthy men showed a drop in testosterone after being restricted to sleeping for five hours a night.
According to the researchers, the most significant effects of reducing sleep duration on testosterone levels occurred between 2 & 10 pm the next day.
A low testosterone level is associated with lower well-being, vitality and erections.
Diabetes
Researchers have shown that inadequate sleep or no deep sleep is linked to a drastic change in the metabolism of the body and the energy conversion. It can increase the likelihood of getting diabetes.
Three nights of sleep disruption can cause the body to lose its ability to regulate sugar levels.
Researchers from Bristol University collected data in April on over 330,000 people who were part of the UK Biobank. Most of them were aged 50 or older.
People who said they regularly struggled to sleep had higher blood sugar levels — a marker of type 2 diabetes.
According to the team, treating insomnia can cause blood sugar levels to drop by as much as losing 14kg (or 3lbs).
The authors of Diabetes Care did not suggest any biological mechanisms for their results.
Studies in the past showed that sleeping deprivation causes insulin resistance and increases levels of cortisol, stress hormone, and inflammation, all which have an affect on blood sugar.
University of Chicago studied the impact of sleeping quality on body’s ability produce insulin. The hormone that controls blood sugar and glucose was examined in a University of Chicago 2007 study.
Five nights of uninterrupted sleep were used to monitor nine healthy young women and men.
They were allowed to go to bed for the first night. Their sleep became disturbed by loud noises that were sufficiently loud to wake them up from deep sleep.
This disruption of deep sleep was comparable to the ageing process. The young volunteers had a higher quality sleep than those in their 60s.
The volunteers received injections of glucose after a night of normal or interrupted sleep. Blood samples were taken to determine how the sugar surge was controlled.
An analysis showed that quality of sleep played a significant role in the body’s ability use insulin to manage blood sugar. Levels rose by alarming 23% following three consecutive nights of unscheduled sleep.
Type-2 diabetes is caused by insulin resistance, or inability to use insulin. It is also linked to obesity.