In this episode I will talk about how sleep affects your health. Many have an intuitive sense that poor sleep leads to poor health but I will highlight exactly what problems you can expect if you don’t have a good sleep routine.
Face it, sleep isn’t sexy. It is seldom seen on the front cover of fitness magazines with a headline “10x your sleep quality in 7 days”. For many, if they need to sacrifice an hour a night to achieve a deadline they will do.
Yet, the quality of your sleep plays a huge part in many other areas of your life.
The longest recorded time without sleep has been 11 days when, in 1965, a student took part in a science fair experiment. Hasten to say regulation was a little bit more relaxed back then. Whilst this experiment didn’t kill him it was noted the student experienced extensive deficits in cognitive function such as concentration, memory and also encountered hallucinations.
In rat studies, the researchers kept the poor rodents awake by rocking the wheel they were positioned on if there was any sign they were falling asleep. They lasted 2 weeks before they died. Whilst this brings up certain ethical issues to attempt on humans, close examples include a teenager who died after a marathon computer games session lasting several days. After being found with his curtains drawn and food containers all around the coroner concluded he died of a stroke.
So we know sleep is important because your brain and body urge you incessantly to engage in it. In fact, we spend a third of our lives sleeping.
How Sleep Works
Before the days of alarm clocks and the standard 9-5, we arranged our day largely around sun rise and sunset. It turns out the clock you have beside your bed is not the only clock your body responds to, our physical and mental processes work to a daily sequence known as the circadian rhythm.
The circadian rhythm functions by responding to light and darkness. See it as an internal timekeeper that coordinates physical and mental processes with the external environment. As Sun rises and daylight beckons our processes operate so we are at our most alert. In fact, based on processes that occur over the 24 hour Circadian cycle we should experience our most alert around 10am.
Equally, as the sun sets our internal processes set up to compel us to prepare for sleep. For example, melatonin, a hormone that acts on receptors in your body to encourage sleep is secreted into your bloodstream around 9pm.
Circadian Rhythm Biggest Influence
Whilst there are a number of factors (such as mealtimes, exercise, body temperature and social interactions) that can influence the circadian rhythm, by far the biggest influence is light.
When light enters the back of your eyes it hits an area of cells called the retinal ganglion cells. It is here where signals are sent to an area of the brain called the suprachiasmatic nucleus that determine at any point in time where the circadian rhythm in the 24 hour cycle.
If everything all falls in line the circadian rhythm will respond as it should. For example night time, it would expect less light, daytime it would expect more light coming in around 6-7am. Yet in this modern, globally connected world, curveballs are thrown all the time.
The big culprit is light stimulation, particularly blue light stimulation.
Sleep & Electrical Devices
In a survey called Sleep in America they found 95% used some kind of electrical device within an hour of going to bed and 61% of those said they used a computer/laptop within an hour of bedtime.
In another within the UK they found 78% of those questioned were exposed to blue light stimulation before going to bed. This doesn’t look like a trend that is going to improve any time soon.
A recent survey found out of nearly 3000 11-18 year olds surveyed 45% admitted to checking their phone after they have gone to bed. Amazingly, 1 in 10 said they checked their phone up to 10 times a night. As we will explore now, it would be impossible to get a good night sleep under these conditions.
In another study, individuals who read electronic books before going to sleep took around 10 minutes longer to fall asleep compared to printed book readers. Additionally they e-book readers also experienced less REM sleep during the night.
Messing with the circadian rhythm can promote problems to your wider health as well.
The 4 Stage Sleep Cycle
Your sleep cycle goes through 4 stages.
The first stage is known as ‘drowsiness’. This is the first stage where the electrical activity in your brain begins to lessen.
Stage 2 is called ‘light sleep’ and not only does brain electrical activity lessen further alterations in background brainwave rhythm becomes evident that aren’t present in a wakeful state.
By the time you reach stage 3, around 30 minutes after first shutting your eyes, you have entered ‘deep sleep’ and show a slowing of brainwaves.
The phases 1-3 take around 60 minutes to play out before you reach the final phase known as Rapid eye movement (REM). You know someone is experiencing REM because their closed eyes move rapidly and brainwaves shows the height of activity. It is at this stage that we dream.
Each cycle lasts around 90 minutes and repeat the cycle between 4-5 times a night. Interestingly, although during the REM stage of sleep our brain waves show a lot of activity all muscles apart from our eyes, diaphragm and Sphincter become all but cataleptic, rendering us unable to move. This is to ensure we don’t act out our dreams.
What happens when sleep goes bad
There are a number of disorders that relate to sleep, one being REM sleep behaviour disorder where the absence of catalepsy during REM sleep allows you to act out dreams. However, the nature of these disorders are too vast for this book so we will only touch upon common sleep troubles rather than disorders.
Through working with clients the common troubles with sleep can fall into 3 categories; Trouble getting to sleep, waking up multiple times in the night and waking up early in the morning and not being able to get to sleep again.
Now all this is rosy when things go well but what happens when you have sleep Troubles
Sleep onset problems is where you lie in bed and just can’t seem to switch your brain off and go to sleep. In a normal setting you have what is known as ‘sleep onset latency’ which is how long it takes for you to go from full wakefulness to sleep. The ideal range is around 20 minutes.
If you stay awake prolonged period of time after this it could be an indicator there is a problem. According to Sleep Specialist Michael Walker to be considered to have sleep onset insomnia you have to have trouble sleeping at least 3 nights each week for more than 3 months.
Cause of Sleep Onset Problems
There can be a number of causes of sleep onset problems. One has been touched upon earlier and that is excess stimulation. If you are still working on your laptop or watching TV (even worse doing this in your bed), the indicator to start initiating sleep is going to be confused.
Another cause of Sleep onset problems is anxiety. Linked to excess stimulation but in a cognitive form. Whilst anxiety is mainly a feelings based condition it is certainly coupled with rumination of thought. Again, not the best setting for sleep. It can also create a perpetual cycle as the anxiety can increase as you get more frustrated about not being able to get to sleep.
Thirdly, room temperature can play a part in not being able to get to sleep. During the 24 hour circadian rhythm cycle your core body temperature lowers around 9-10pm your body gets set for the sleep state. If your room feels like its seconding as a sauna, your body is going to have to work harder to maintain the lowered body temperature. It is also more uncomfortable when trying to sleep in a warm stuffy environment. Sleep scientist Michael Walker comments in his book “Why we sleep” it is a common sight to see people hanging their extremities (hands and feet) out from under the duvet to help cool the inner core temperature.
Waking up too early?
When persistent this can be diagnosed as sleep maintenance insomnia (at least 3 times a week over 3 months is one of the criteria). Some of the reasons for this are similar to the problems with getting to sleep. Temperature can play a large part for example.
Also as we age our sleep cycles become shorter. This can be problematic if, naturally, you have a habit of going to bed at 10am and due to shortened cycles you start waking up at 4am. Another factor is alcohol. While many feel it can help them sleep better, it actually acts more as a sedative so don’t go into the regular sleep patterns you would do when not drinking alcohol.
As a busy professional you can get a sense of the importance of good sleep. But lets look at The Consequence of poor sleep
Anyone that has had a couple days of disrupted sleep don’t need a book to tell them the effects aren’t desired. Having been to a number of music festivals I can testify that a combination of drunk people around the campsite, the hardened floor and questionable hygiene means by the end the only thing you’re focussed on is the image of your bed in your mind.
Disrupted sleep can hinder many areas of your health. It creates a knock on effect like a virus swarming around your environment.
Poor Sleep affects 3 Key Areas
3 areas it is particularly pertinent is weight, cognitive ability and aging.
Weight and sleep
It is correct to say weight is about calories in vs. calories out. However, to stop there would be naive. The influences that play on either side of that equation are vast and sleep is one of them.
There are two areas where poor sleep can affect weight gain; hormonal responses and decision making. In terms of hormonal responses a number of studies have shown that poor sleep can increase your hunger response.
In one study 14 health non-obese individuals were placed on a fixed calorie diet and had one group sleep for 8.5 hours and the other group sleep for 4.5 hours for 4 days. Both groups took part in both conditions 4 weeks apart.
In the days following 4.5 hours sleep participants showed increased activation in the endocannabinoid (eCB) system. This also coincided with times when they reported elevated feelings of hunger.
Interestingly, after the 4th day evening meal all participants fasted until the afternoon of the 5th day where they were able to choose their own meals and snacks for the rest of the day. While both groups ate 90% of their daily intake in the first meal they got on the 5th day, the sleep deprived group snacked more on the unhealthier snacks available to them.
In the area of fat accumulation, a 5 year study followed 1097 people found a significant increase in both visceral fat (fat around the organs) as well as subcutateous fat (fat under the skin) in participants with a habit of sleeping less than 5 hours a night. In addition to this study, a meta analysis featuring 56,000 participants showed an link between shorter sleep durations and fat accumulation around the stomach/waist area.
How Poor Sleep Affects Decision making
The decision making around food when sleep deprived is the second problem area. This is because poor sleep can affect how we perceive risk and reward.
To highlight this, one study featured 29 volunteers who were either told to sleep in their usual way or pull an all nighter and miss a nights sleep. Following this they were then given a series of gambling tasks whilst lying in an fMRI scanner. The results showed the group who had a night of no sleep took more risks to get the potential gains & had little concern for the losses they suffer. Their brain scans reflected this by showing increased activity in the brain reward areas.
2 hormones that play a key part in decision making related to your weight is ghrelin and leptin. Ghrelin is known as the appetite hormone because it signals to the brain its time to eat. Ghrelin is supposed to be suppressed when you sleep for obvious reasons (the last thing you want at 2am is a signal that you are hungry).
Leptin is another hormone that communicates with the brain relating to appetite, only this time communicating when you are supposedly full. So you can see, Ghrelin and leptin work hand in hand when communicating appetite where one indicates you need to eat (high levels of Ghrelin) and one indicates when to stop eating (high levels of Leptin). When you are asleep Leptin levels are increased indicating your energy levels are fine and there is no need for food consumption.
However, there is evidence short sleep durations puts these 2 hormones in reverse of what they are supposed to be. In one study of 1024 participants they found the people who were sleeping for around 5 hours had close to 15% higher levels of Ghrelin and 15% lower levels of leptin in their system compared to those who were sleeping for 8 hours. It doesn’t take much either.
In another study, participants were tasked to sleep for 7 hours, 4 hours and total sleep deprivation with gaps in between the sleep periods. The results showed even after 1 night Grehlin levels had increased by over 10% on the total deprivation night and only slightly less on the 4hour sleep. In this particular study, leptin levels remained unchanged however another study showing the effects of 6 days of 4 hour sleeping pattern showed a 26% reduction in leptin levels compared to fully rested sleep.
Sleep and cognitive ability
As a busy professional it is fair to say you have to be on the ball when in the workplace. In meetings, around the desk, interacting with colleagues, the cognitive demand is ever present.
The role sleep has in ensuring your cognitive ability is work ready can not be understated. Sure, work ethic and pure grit can get you through the odd day but what if poor sleep quality becomes prolonged? The outlook doesn’t look great.
In one study looking at the 8 day sleep data diary of 130 middle aged workers researchers were able to predict the level of off-task periods and distracting thoughts based on the quality of sleep the night previous. They found that for every 16 minutes of less sleep they got resulted in one less point on the cognitive interference scale the study used.
A large part of workproofing your brain and body is to consistently make ‘health seeking behaviours’ while also consistently doing less ‘health inhibiting behaviours’.
There is a suggestion that poor sleep quality makes you more likely to do the latter rather than the former. In a paper by the centre for disease control they looked at the association between sleep duration and health risk behaviours. They found those that slept less than 6 hours were more likely to engage in health risk behaviours such as smoking, physical inactivity and increased alcohol consumption. Interestingly they also found a similar case for those sleeping over 9 hours which suggests there is an optimal zone for sleeping between 6-9 hours.
Further studies have confirmed how poor sleep negatively affects short term memory, response time & accuracy , the ability to divide your attention and auditory attention.
While many reading this are unlikely to face many periods where you go to work after 12-20 hours sleep deprivation, it is worth noting that prolonged poor sleep quality is likely to create a similar phenomena when looking at what the studies have found as a collective.
Sleep and Aging
If you were to be asked your age it is highly likely you would reply with your chronological age. However, you also have another age, your biological age. This is the measure of how your various physiological systems are aging including your organs, tissues and blood. In some ways this is a more important measure to be aware of because it is a direct reflection on your level of health.
Sleep is a big influence on aging both in terms of appearance and the likelihood of metabolic diseases. It doesn’t have to take much either. In one study they should just 4 hours of short sleep over 4 nights can reveal changes on a molecular level that promote premature aging.
Your skin is the most visual aspect of premature aging and there is evidence to show poor sleep quality accelerates the rate of aging. In a study featuring 60 woman, some were rated as good sleepers while others were rated as poor (5hrs or less).
The results of the study showed the poor sleepers has worse scores on intrinsic skin aging (Levels of collagen & elasticity of skin for example), significantly higher levels of transepidermal water loss (TEWL) (amounting to higher rates of dehydrated skin) and recovered worse 24 hours after exposure to ultraviolet light. In addition to that nightmare, the poor sleepers also had a worse perception of their appearance and physical attractiveness.
The effect of poor sleep quality on aging doesn’t just go as far as your skin. A number of metabolic diseases can be attributed to the quality of your sleep as well. In a study looking at 48000 individuals scientists looked at telomere length.
Telomeres are caps at the end of DNA strands that protect it in order for the DNA to replicate. As you naturally age these telomeres reduce in size making them less protective of the DNA strand. The scientists were able to find a causal link between premature telomere shortening and a variety of metabolic diseases such as colorectal cancer, coronary heart disease and celiac disease.
Cognitive Decline & memory
It is a common feature of aging to see cognitive decline. One area of decline is memory, however this is exacerbated by consistent short sleep. A meta analysis (study of studies) looking at self reported measures of sleep compared with numerous cognitive tests including memory found a clear connection between short sleep and extent to the impairment in the tests. This was still the case when similar studies accounted for other factors that could influence elder populations such as medication, cardiovascular issues and depression.
If your pension is a way of saving throughout your life to ensure you are a little more financially stable in your later years, your lifestyle provides the same stability for your later years health. Sleep is one of those factors you need to nurture, as shown in a study of following over 2300 Finnish Twins during a 20 year period from 52 years old onwards.
The study found those that reported sleeping less than 7 hours & more than 8 hours, had poor sleep quality and used sleep medication more than 60 nights of the year were 1.8 times more likely to Alzeimers disease.
In another study featuring over 17,000 older adults, 4 factors were taken into consideration; Sleep problems and fatigue in the last 6 months, medication use and recent sleep problems or change in pattern. The study found those who scored highly on the 4 factors were 23% more likely to develop dementia or Alzeimers disease. This was after factoring out other age related components such as BMI as baseline cognitive performance.
It is clear from these findings, poor sleep will not only diminish your cognitive performance and exterior signs of aging, it also heavily increases your chances of developing Alzeimers or dementia in the later years of your life as well.