Much of this post is taken from research by Dr Matthew Walker – UC Berkeley with protocols by Dr Andrew Huberman – Stanford School of Medicine.
Sleep Fundamentals: QQRT
Quantity: the total amount of sleep. The typical adult needs 7 to 9 hours of sleep per night, which gives sufficient time for deep sleep and REM sleep, so you wake up refreshed and restored. Some people need less, others more, especially babies, teens, and those combating an illness or infection.
Quality: the continuity and structure of sleep. Frequent awakenings (even if you don’t remember) or fragmented sleep represent poor sleep quality.
- Wearable sleep trackers measure sleep quality through sleep efficiency scores. An efficiency rating of ≥ 85% is a good goal.
- Note: For some, sleep trackers can lead to anxiety about sleep quality (termed “orthosomnia”), which can paradoxically lead to disrupted sleep. Consider reviewing your sleep scores less often. For example, weekly, not daily, to minimise constant monitoring.
- For those who don’t use sleep trackers, poor sleep quality often manifests as excessive daytime sleepiness even if they slept sufficient total hours.
Regularity: stick to a consistent sleep schedule. Consistently going to bed and waking up at a similar time each day improves overall sleep patterns and quality by anchoring your body’s circadian rhythm, or internal clock.
- Aim for consistent bedtimes and wake times with a ± 30 minutes margin of error, whether it’s the weekend or a weekday. No one is perfect about this, but that’s a good goal.
- In addition to your morning alarm clock, consider adding a “bedtime alarm,” which tells you when to go to sleep.
- Studies have shown that regular sleep patterns reduce all-cause mortality and may reduce the risk of cancer and cardiovascular disease more effectively than other metrics, such as sleep duration.
Timing: align your sleep schedule with your natural chronotype (morning person, night owl, versus typical sleep-wake schedule). Chronotype is primarily determined by genetics, and yet your preferred sleep time will vary across your lifespan. You can find your natural chronotype using the Morningness-Eveningness Questionnaire (MEQ). Sleeping out of sync with your chronotype will result in poorer quality sleep. But, of course, we have to adhere to life’s demands as well.
What Happens When You Fall Asleep?
Data on the two types of sleep was published in 1954, then in the 1960s William DeMent carried out studies and coined the name REM (Rapid Eye Movement). Every time someone went into REM sleep they would be woken to do a mathematical task. After day three of selective REM sleep deprivation they started to show signs of paranoia, then to have hallucinations and delusions and by day five they were having aspects of severe psychosis. This research was summed up by an American entrepreneur called E Joseph Cossman. He summarised it in a single sentence as ‘the best bridge between despair and hope is a good night of sleep’ and to this day that’s exactly what the data demonstrates in terms of basic emotional brain function.
In the first 20 minutes of falling asleep, you enter non-REM sleep, which has four stages, 1 & 2 are light and 3 & 4 are deep non-REM. During these first 20 minutes, your heart rate slows and brain wave activity reduces. After 20 minutes you enter stages 3 & 4 and your heart rate drops dramatically, muscle tone drops and hundreds and thousands of cells in the Cortex all fire up and then go silent. At around 60 to 70 minutes into the sleep cycle, you return to stage 2 non-REM and at around 90 minutes go into REM sleep.
Just before you enter into REM sleep a signal is sent through the brain stem to the alpha motor neurons in the spinal cord to prevent them from working. This effectively paralyses your body during this dreaming phase allowing you to dream safely. Your involuntary muscles are not paralysed ensuring you can breathe and your heart continues to beat, nor are the eye or ear muscles paralysed.
This sleeping cycle continues throughout the night with more 3 & 4 non-REM in the first half of the night and more 1 & 2 non-REM in the second half, along with more REM sleep.
Sleep Deprivation
One of the earliest and strongest effects of a lack of sleep is the absence of motivation, not interacting with the world, not wanting to be social, not wanting to learn, not wanting to exert effort, not wanting to exercise, not wanting to do much of anything.
A lack of sleep will impact every physiological system in your body and every operation of your mind. If limited to 4 hours for one night, there will be a 70% drop in natural killer cell activity; these cells are critical anti-cancer immune cells. A global experiment called Daylight Savings Time is carried out twice yearly in 70 countries with 1.6b people participating. In the Spring, when 1 hour is lost of sleep, there is a 24% increase in heart attacks the following day. Conversely in Autumn, when 1 hour is gained in sleep, there is a 24% decrease in heart attacks. It has also been noticed that in the Spring not only is cardiovascular health at risk, but there is also an increase in diabetes and obesity, poorer mental health, lower cognitive performance, and an increase in the risk of motor vehicle accidents. Lack of sleep reduces levels of testosterone in men and oestrogen in women, and systolic blood pressure increases along with heart rate contractions. The progression into obesity diabetes, cardiovascular disease, mental health issues, anxiety, depression, suicidal ideation, and immune-compromised infection will be mid-term consequences with a longer-term slide into premature mortality.
A group of healthy people with no signs of psychiatric illness or emotional instability were given a full night of sleep and the next day they were placed inside a brain scanner and shown a range of emotional visual images ranging from very neutral to quite unpleasant and negative. The study was to see how the brain reacted to those emotional experiences with and without sleep. The structure that was initially focused on was the amygdala situated on the left and the right side of the brain. The amygdala is the centrepiece region for the generation of emotional reactions both positive and negative but this study focussed on the adverse, negative aspect. In people who were sleep-deprived relative to those who had a full night of sleep, there was a 60% increase in emotional response rate. This was a dramatic heightening of sensitivity to the initial triggering of the emotional response, and the more the emotion became the more separate the two sets of reactivity curves came from the amygdala. The question then became why is the amygdala so reactive and uncontrolled when you are absent of sleep? Another analysis was carried out and a structure in the frontal lobe that sits right between your eyes, the medial prefrontal cortex, was investigated. This acts like a control rational mechanism on the deep emotional brain centres, placing the context to an appropriate or inappropriate reaction to a situation. With sleep deprivation, it was found that the connection had been severed so the emotions could not be modulated effectively. A Japanese research group replicated this more rigorously and their published findings had the same response.
Sleep Hygiene Basics
Light & Dark
The hormone Melatonin has many functions, one is to make you sleepy. Darkness allows the release of melatonin to signal the onset of sleep. Bright light, especially at night, potently inhibits melatonin. This causes you not to feel as sleepy and, consequently, to get poorer quality sleep.
- In the evening, dim the lights in your home to signal the body that it’s time to wind down. Avoid viewing bright overhead lights between 10 pm and 4 am. Here is a simple rule: only use as much artificial lighting as is necessary to move about safely at night. Use low-positioned lights (rather than overhead) and yellow or, even better, deep orange/red lightbulbs, if available; they are less stimulating than typical lights.
- Minimise screen time at night. If you’re on a screen, dim it way down. Additionally, many computer operating systems show warmer colours at night. There are also apps like f.lux (zero-cost) that allow for dimming. This also applies to mobile phones, if possible leave your phone outside the bedroom.
- Add blackout curtains or wear an eye mask to maximise darkness in the bedroom.
- Within 30-60 minutes of waking, go outside for 10-15 minutes of morning sunlight. Sunlight suppresses Melatonin and resets your circadian rhythm. Morning sunlight also triggers Cortisol release to help you wake up and stay more alert during the day. On overcast days look towards where the sun will be as plenty of light (photons) penetrate cloud cover. On bright cloudless days: view morning and late afternoon sun for 10 min; on cloudy days: 20 min; on very overcast days 30-60 min. Consider an artificial daytime simulator source if you live somewhere with minimal light. If you wake up before the sun is out and want to be awake, turn on artificial lights and then go outside once the sun rises.
- Looking through an indoor window does not work. Don’t wear sunglasses for this practice if you safely can, but contact lenses and eyeglasses are fine. Don’t look directly at the sun, and never look at ANY light so bright it is painful to view!
- If you can’t get natural morning sunlight due to geographic location or schedule, artificial bright lights like seasonal affective disorder (SAD) lamps are a substitute, though less effective.
Temperature
Temperature plays a crucial role in sleep regulation and to fall asleep, core body temperature must decrease by approximately 2-3°F (1°C).
- Keep your bedroom cool (~67°F or ~19.4°C), or use a temperature-controlled mattress cover.
- Place your hands or feet from underneath the covers to help cool down.
- Taking a warm bath or shower before bedtime is a science-supported method to improve your ability to fall asleep and improve deep non-REM sleep. The warm water initially raises core body temperature, but subsequent cooling occurs to help to fall asleep.
Food & Meal Timing
The effect of food on sleep largely depends on appetite, circadian rhythm, and personal preference. Experiment with different foods and timing to see what best supports your sleep.
- For most, eating approximately 2 hours before bedtime doesn’t typically impact sleep. Eating closer to bedtime can increase the likelihood of gastric reflux (heartburn) and impair sleep in some individuals. Again, this is highly individual. If you do, make it a smaller snack or meal, but also don’t try to sleep while overly hungry. Most people can’t.
- Avoid excessive fluid consumption before bedtime to reduce the likelihood of waking up throughout the night.
Caffeine
The health benefits associated with coffee drinking are good from a health perspective. However, it has nothing to do with the caffeine, It’s because the coffee bean contains a large dose of anti-oxidants, the most powerful being chlorogenic acid. Studies with decaffeinated coffee give very similar health benefits so drink caffeine but limit yourself to about 2 cups of coffee, 3 cups of coffee maximum. Caffeine is a stimulant it does not reduce the need for sleep; it only temporarily masks sleepiness. Once caffeine wears off, a buildup of adenosine, a chemical that promotes sleepiness, causes a “caffeine crash,” which usually occurs in the early afternoon.
- The timing of drinking caffeine is crucial for sleep quality. So, if you have trouble sleeping, don’t reach for a late afternoon cup of coffee. Instead, consume caffeine early in the day and not within 8-10 hours of bedtime. caffeine has a quarter-life of somewhere between 10 to 12 hours so if you have a cup of coffee at midday a quarter of that caffeine is still in your brain at midnight
- Note: some people say they can sleep after ingesting caffeine in the afternoon or evening. This is likely due to tolerance and/or differences in how they metabolise caffeine. Do what works for you, but know it can negatively affect sleep structure, including REM duration.
Alcohol
Alcohol is a sedative, not a sleep aid. While a ‘nightcap’ may help you get to sleep quickly, alcohol impairs the natural structure of sleep. You don’t remember how you have slept but the quality is poor alcohol is very good at blocking your REM sleep and disrupting your deep non-REM sleep. Also, even the smallest amount of alcohol causes fragmented sleep.
Taking Naps
Naps can improve cardiovascular health, lower blood pressure, and improve your learning and memory abilities. Negative emotions can be de-escalated and positive emotions increased. However, be careful if you take naps. Try not to nap for longer than 20 minutes because once you go past 20 minutes you fall into the deepest stages of non-REM sleep. If you wake up after about 45 minutes or 60 minutes you’re going to feel almost miserable and worse than you did before the nap because you have sleep inertia, essentially a sleep hangover and it can take you almost an hour before you feel like you’re back up to operating normally. In addition, don’t nap too late in the afternoon (3 pm) and if you’re someone who has insomnia or sleep difficulties do not nap because when we’re awake during the day we build up a sleepiness chemical called adenosine and the longer that we’re awake the more adenosine builds up. After sleeping a full night the brain has evacuated all of the adenosine so that when we wake we feel refreshed and restored. When you take a nap you’re releasing some of that healthy sleepiness
Wind-Down Routine
Much like slowing down a car before stopping, a ‘deceleration’ from the day’s activities is essential for good sleep. Establish a wind-down routine to prepare the body and mind for sleep:
- Engage in relaxing activities, such as meditation, listening to music, podcasts, sleep stories, or reading a book.
- Avoid stimulating activities before bed, such as watching television, reading the news, strenuous exercise, or social media.
- Expect to feel alert ~1 hour before your natural bedtime. This is a naturally occurring spike in wakefulness that sleep researchers have observed and will pass.
Trouble Falling Asleep?
Walk It Out: If it’s taking longer than ~20-25 minutes to fall asleep or back asleep, leave your bed and go elsewhere in the house to engage in a relaxing activity. The goal is to prevent an association between a state of wakefulness and your bed, as this can lead to future difficulties falling asleep. Only return to bed when you are truly sleepy and be mindful not to fall asleep in another location; you want to relearn the association of sleep with the bedroom.
Do Nothing: After one poor night’s sleep, avoid compensatory behaviours such as sleeping later, going to bed early, increasing caffeine intake, or excessively long or late-day napping. These behaviours can disrupt your natural circadian rhythms and may negatively affect sleep-wake cycles—in other words, they will make it hard to get back on your usual schedule.
Mental Walk: If you have trouble falling asleep, take a “mental walk” and visualise walking a familiar route. This technique will redirect your focus away from ruminating thoughts to help you fall asleep.
Other Help – YouTube. If you wake up in the middle of the night and cannot fall back asleep, consider doing a Non-Sleep Deep Rest (NSDR) protocol when you wake up. Enter “NSDR” into YouTube and the top 3-4 options have different voices and durations for you to select from. Or do a “Yoga Nidra” protocol (enter “yoga nidra” into YouTube).
Limit Daytime Naps: Keep naps short (≤ 20-30 minutes) and no later than the early to mid-afternoon to avoid impacting your nighttime sleep.
If you try these protocols and don’t notice a difference, you might be suffering from a sleep disorder. Seek professional help if you experience persistent problems, which might be due to sleep apnea or true insomnia.
Cleansing the Brain
Sleep expert Dr Matt Walker (professor of neuroscience at the University of California, Berkeley) says,
‘We have not been able to discover a single psychiatric condition in which sleep is normal so there is a direct relationship between your sleep health and your mental health’.
One of the functions of emotions when it comes to memory is to prioritise that experience instructing the brain that this information is relevant to us as an organism. During good quality sleep between the initial experience and the later recollection of that emotional memory, the brain has divorced the emotion from the memory so on recollection at a later time, the emotional memory is no longer as powerfully emotional as it was at the time of the experience. The sleeping brain can detox the emotional memory. In a study, a biological model of exactly how this works was carried out studying a sleep group that had eight hours of sleep which was measured. It was found that the greater the amount of REM sleep the greater the amount of emotional detox experienced the next day.
Something utterly unique happens during sleep, with levels of noradrenaline completely shut off, the only time during 24 hours there is a complete cessation of adrenaline in the brain. (The chemicals noradrenalin (UK) and norepinephrine (US) are the brain equivalent of adrenalin and epinephrine found in the body). The neuromodulator Serotonin is also blocked. So the stress-related chemicals in the brain are switched off during REM sleep.
However, levels of another chemical Acetylcholine increase in the brain. Acetylcholine also acts at various sites within the central nervous system, where it can function as a neurotransmitter and a neuromodulator. It plays a role in motivation, arousal, attention, learning, and memory. There is almost a 30% increase in some brain regions than when awake pointing to REM sleep as the perfect condition for emotional overnight therapy where you can reactivate, experience and process those emotional memories in a chemically safe environment that allows you to strip away the emotion.
This resembles behavioural desensitisation therapy used to treat trauma, whereby under the care of a qualified psychiatrist or psychologist somebody will be encouraged to recall in great detail some traumatic event and through repetition and with support will be allowed to encounter the experience safely over several sessions so the emotional load of the event is diminished
To be your best emotional self and access positive emotions to their full amplitude, the best and cheapest non-psychological way to enhance your sleep is to sleep an extra 15 or 20 minutes.
Anxiety
Anxiety is probably one of the greatest enemies of sleep and is one of the principal reasons that underlies insomnia. If you have stimulants in your system before going to bed such as alcohol, drugs or caffeine your fight-or-fight branch of the nervous system is triggered and you feel what is called the tired but wired phenomenon. You start to worry, then you start to ruminate and when you ruminate you catastrophise and when you catastrophise you are awake for the next two hours or so. We have the sense that in the darkness of night, things are so much bigger than they are in the brightness of day and we start worrying. A study on the consequences of a cup and a half of strong caffeine intake before bed showed it strips away your deep sleep by somewhere between 15 to 30% . To put that into context if you drop your deep sleep by 30% it would be the same as ageing you by about 40 years. Even if you fall asleep and you stay asleep you’re not aware of the lack of deep sleep that you’re not getting because of the caffeine. Deep sleep is critical for regulating your cardiovascular system and replenishing the immune system, it also regulates your metabolic system, controlling hormones such as insulin that will regulate your blood sugar. Deep sleep will strengthen, consolidate and secure new memories in your brain preventing those memories from being forgotten, deep sleep is also the time when we cleanse the brain of metabolic toxins, particularly those related to Alzheimer’s disease.
Suicide
It has been found in studies that insufficient sleep is a precursor to suicide. Sleep disruption seems to predict suicidal ideation; suicidal thinking, suicide planning and tragically suicide completion as well.
PTSD
Paul Conti, the renowned psychiatrist, defines trauma as some adverse event that changes the way that our nervous system works such that we function less well in the future. The diagnostic criteria for PTSD is not just being able to fall asleep it’s specifically having repetitive nightmares. As mentioned earlier, in normal REM sleep noradrenalin is switched off and emotions are stripped away from the memory. However, it has been found that PTSD patients have heightened levels of noradrenalin as a basal state as well as during REM sleep so the trauma remains a vivid emotion linked to the memory.
Alzheimer’s Disease
Whilst diet and genetic factors dictate the risk of developing Alzheimer’s in later life, there is causal evidence both in animal models and in human models that if a human being is deprived of deep sleep for a single night the risk of developing Alzheimer’s increases. Sleep deprivation causes an immediate increase in the two proteins, beta-amyloid and tau associated with the development of Alzheimer’s, circulating in the bloodstream and cerebral spinal fluid that bathes the brain. Maiken Nedergaard, professor of neuroscience at the University of Rochester, USA discovered the brain has a cleansing system called the glymphatic system named after glial cells that make it up. This system is switched into overdrive during deep non-REM sleep and washes away the build-up of beta-amyloid and tau proteins. If you’re not getting enough good quality sleep every night it doesn’t mean that you’re going to get Alzheimer’s disease next week or in a year but over time it is now believed through this causal mechanism that insufficient sleep is a risk factor for Alzheimer’s disease.