How much sleep do we really need - and what if we don't get it?
An occasional night without sleep makes you feel tired and irritable the next day, but it won't harm your well-being. However, chronic poor-quality sleep can have dire health consequences, writes Regina Lavelle
In her 2016 book, The Sleep Revolution, Huffington Post founder Arianna Huffington revealed her conversion to the church of good sleep took place after she collapsed breaking a cheekbone; her doctors told her it was because she was exhausted on a nightly sleep of three to four hours.
Speaking in a Fast Company interview to announce her new health and wellness start-up, Thrive, Huffington likened sleep deprivation to "the new smoking".
"The impact on our health is dramatic," she said. "We have all the data now that shows how it affects every aspect of our health."
Indeed, announcing in 2017, that: "Sleep is the new status symbol", The New York Times outlined the consequences of poor sleep.
"Good sleep helps brain plasticity [the adaptability of your brain], studies in mice have shown; poor sleep will make you fat and sad, and then will kill you."
Interestingly, given the current prevalence of flu, Dr Seamus Linnane, consultant respiratory physician, says that: "Influenza immunisation is less effective in those to have had a recent sleep disturbance. Susceptibility to other viruses such as the common cold is greater in those with poor quality sleep."
So how much sleep do we need?
According to research published by PHE (Public Health England), adults who sleep fewer than six hours a night have a 13pc higher mortality risk than those who sleep at least seven.
Additional PHE research shows that those sleeping fewer than seven hours a day are 30pc more likely to be obese than those who sleep nine or more.
Poor sleep is also bad for the economy. In the UK, they estimate that lost sleep costs the Exchequer £30bn annually with 200,000 working days lost because of poor sleep.
With this in mind, the fact that LinkedIn, the professional social network, has its own 'Sleep Ambassador' who "designs sleep education and training programmes for a number of Fortune 500 companies." seems less like altruism and more like financial sense.
A study conducted for Laya Healthcare in August 2018 revealed the pernicious nature of poor sleep - 46pc of respondents in the Empathy Research study reported they were anxious because of poor sleep (second only to anxiety caused by financial problems) whereas in a question on the impact of anxiety, 56pc - the highest number - reported they slept poorly because of anxiety.
Dr Sarah O'Neill, an occupational psychologist who deals with mental health issues and works with Laya, says: "Sleep deprivation is one of the single best predictors of mental health issues. Poor sleep is associated with many mental health disorders, including anxiety and depression."
Dr John Garvey is Clinical Director of Sleep Laboratory at St Vincent's Hospital in Dublin. Dr Garvey see patients with the gamut of sleep complaints - from circadian rhythm disturbances, when you can't sleep at night and can't wake up in the morning, to narcolepsy and parasomnia, "people who do weird things in their sleep. This is talking, walking, night terrors, some patients eat or have sex in their sleep."
Dr Garvey says that there is a relationship between lack of sleep and depression and anxiety. "There is a 50pc association between insomnia and depression and anxiety. Now, it may be a chicken and egg effect that if you're anxious you may have difficulty getting to sleep so it becomes a vicious cycle."
What is good-quality sleep?
Specialists agree that this area is particularly difficult to define. As Dr Linnane, who undertakes sleep studies at the Blackrock Clinic and Beacon Hospital, puts it, "the mechanisms and effects of sleep can vary from person to person."
"Good quality sleep is defined as sleep of sufficient duration without excessive arousals. Arousals or repetitive awakening can reduce the quality of sleep irrespective of the total duration of the sleep time. An arousal may last mere seconds and may not be remembered by the sleeping person the next morning.
"Increases in ambient noise and variations in room temperatures may be enough to trigger an arousal. An average of five arousals per hour can significantly disrupt sleep quality and lead to impairment of functioning the following day."
The bad news is there is no Goldilocks zone for good-quality sleep - no defined set of parameters within which sleep occurs. It varies on a night-to-night basis.
"Your sleep changes as you through your life," says Dr Garvey.
"The reason there are no fixed measurements is that sleep is a physiological state. If you take somebody who exercises at a point in their day - that lends itself to a change in their physiological state; increases in heart rate, changes in blood pressure. A soccer player will not have the same physiological profile for every match either.
"It doesn't mean we don't need to study it further. We may learn a lot more when we start to apply big data."
Am I getting quality sleep?
"The best way of knowing if you are getting good-quality sleep is if you are waking up feeling alert and there is an absence of sleepiness during the day," says Breege Leddy, Manager of Sleep and Clinical Physiology at the Mater Private Hospital.
"You should fall asleep within 20 minutes of going to bed, stay asleep for approximately 90pc of the time you are in bed. There should be no excessive movements, abnormal behaviours, pauses in breathing or snoring during sleep," she adds.
"The most obvious sign of a poor night's sleep is feeling sleepy the next day. Our concentration can be poor, we tend to be more irritable, our ability to perform tasks such as driving can be compromised and we are not able to function to the best of our ability."
One of the issues with poor sleep is that tiredness creeps up on us when, as Dr Linnane puts it, we're completing "monotonous, boring or repetitive tasks", which for many people can summarise a day's work.
"The length of sleep necessary for good quality varies from person to person and also changes during the course of a lifetime," he says. "Recently revised guidelines suggest seven to nine hours as an average.
"The commonest reason for shortened sleep length is a reflection of our modernised and busy society. I have read one study which suggests a reduction in sleeping time for schoolchildren of 0.75 minutes per year during the course of the last century.
"Later bedtimes and earlier rising times are often sacrifices made by those with long commutes and long working days. Distractions from TV, phones and computers can also lessen the amount of time we spent asleep in bed."
How is sleep quality measured? (And is my watch any good?)
To test sleep, doctors use a range of measurements, including EEGs (Electroencephalogram) and detect heart rate, brain waves and eye movement. They also use actigraphy, a sensor placed on the non-dominant wrist to assess muscle movement.
Yes, it sounds like the wearable that's probably on your wrist right now, but Dr Garvey says: "Wearables will use algorithms using surrogate markers rather than directly measuring those markers we monitor in a sleep lab to give an estimation of sleep stage.
"For example, when you dream the reason you don't kick your foot when you're dreaming of kicking that goal is that there's a protective measure in your body which prevents the limb from moving, so it's looking at heart rate to indicate these changes..
"If someone comes into the lab and says, 'This is what my watch says is happening, I take it with a generous pinch of salt'."
Dr Linnane says that lab measurements are necessary to make an accurate determination of sleep quality since "an individual's recollection of arousals is unreliable and hence an analysis of brainwave activity during sleep is required."
The sleep cycle
Sleep is divided into REM (Rapid Eye Movement) sleep and Non-REM sleep.
Breege Leddy says that when it comes to sleep "we need to focus on quality as opposed to quantity. You can sleep for long periods but if the quality is not good you will wake up not feeling refreshed. In order to determine whether someone is asleep we measure brain activity by means of EEG. EEG activity changes frequency within each of the different stages of sleep - Stages N1, N2, N3 and REM."
◊ N1: The period just after falling asleep
◊ N2: Takes up 45-55pc of total sleep time
◊ N3: Where delta waves - recorded by the
EEG - are observed 20pc of the time
◊ REM sleep occurs in the last third of our sleep
Dr O'Neill explains how we progress through the cycles.
"We generally spend about 25pc of our sleep in REM, and the other 75 in non-REM. Our bodies can vary the time spent in each stage, but in a normal 90-110 minute sleep cycle, it takes approximately 40-50 minutes to reach deep sleep. Four to five full sleep cycles equates to around eight to eight-and-a-half hours sleep per night," she said.
The nemeses of sleep: when we're our own worst enemies
A whole industry has grown up around getting us to sleep but Dr Garvey and Dr O'Neill agree that stimulant use should be addressed.
"Drinking a lot of alcohol before going to sleep might help you nod off easily but it will affect your ability to stay asleep," says Dr Garvey. "It promotes sleep maintenance insomnia and leads to a dysfunctional belief or behaviour that you can't get back to sleep."
I put it to Dr Garvey that we can get so worried about sleeping that we don't sleep.
Sometimes, he agrees, that when people are concerned about poor sleep they will generate an anxiety in this area.
"People start to overthink their sleep. That's where CBT (Cognitive Behavioural Therapy) addresses fixed beliefs or behaviours."
How poor-quality sleep can affect your head
A good night's sleep is key to having good mental health. "Poor sleep is associated with many mental health disorders," says Dr O'Neill, "including anxiety and depression.
"Sleep deprivation causes the amygdala - which is associated with mood regulation and emotion - to become more active. This means you are more likely to be moodier, more irritable and have more excessive emotional reactions to stimulus, when lacking sleep. This can occur after just one night of sleep deprivation."
Sleep deprivation over time can also, Dr O'Neill says, "predict neurodegenerative diseases such as Alzheimer's."
This is exacerbated as we get less quality sleep as we're older.
"The average 70-year-old gets 10pc of deep sleep rather than 20pc in earlier stages of your life. There can be a lot of reasons for this - high blood pressure, arthritis, medications can have an effect, and then there can be an increased need to use the bathroom which interrupts sleep."
Sleep hygiene - why routine matters
There's good reason to be sceptical about much of what we're advised to do - and buy - for a good night's sleep, but the basic principles of what is known as sleep hygiene (without the expensive accoutrements) are science-based.
Says Dr Linnane: "The principles of good sleep hygiene have been applied with success for many individuals. This approach aims to ensure that the person retires to bed in a calm and unstimulated state at a regular and consistent time. Obviously shift work and antisocial working hours can cause people significant disruption and difficulties. Cognitive behavioural therapy with a specific focus on sleep has shown great promise."
A cool environment, no phones, unfussy bedding - how to get the bedroom right
Sleep expert Lucy Wolfe of sleepmatters.ie says we should aspire to a "sanctuary sleep space. Your bedroom should be a cool environment - heated to roughly 12-16°C - the coolest room in your house.
"The smallest bed you should be sleeping in as an adult is a double as there should be plenty of space to move around.
"Mattresses need to be changed every seven to 10 years and as you age mattresses should meet the increased need for support.
"Sleep in clothes you like the feel of, and bedding should be made of cotton or breathable materials. The pillow should fit between your head and your shoulders.
"Bedrooms should be cleaned and aired daily - open blinds and windows and clean for dust mites. At night the room should be dark."
O'Neill too agrees that bedrooms should be device-free.
"The evidence is that bedrooms should not have devices. Only use the bedroom for sleeping and sex."
What do you do if you are worried about your sleep?
"The first thing is to see your GP," says Dr Garvey. "You GP can tease that out. The first symptom of a lot of sleep disorders is sleepiness. Other conditions can cause it but often, first of all, will cause fatigue, which is a psychological sense of feeling tired all the time. A GP will check the iron levels are okay, B12, thyroid function is fine, adrenal glands normal. And that will allow them to frame it correctly and tease out the pertinent factors.
"From there, if you need a specialist review, they can point you in the direction of a specialist."
Lucy Wolfe's top tips
◊ Address your bedroom area and make it as relaxing as possible.
◊ Consider your stimulant use - caffeine, alcohol, nicotine etc. and cut down.
◊ Mind your stress levels. Get underneath the issue. Practice some mindfulness. Stop the negative thought process.
Stop the cycle of tension.
◊ Keep a sleep diary.
◊ Don't exercise too close to sleep time.
◊ Develop a pre-sleep ritual.
◊ Remove electronics from the bedroom,
◊ Bathe before bed. A bath will heighten your body temperature, causing it to drop before bed, relaxing you further.
Health & Living