We still don’t know why creatures need sleep.
After literally centuries of research, sleep remains one of the most poorly understood areas of biology.
Dr Allan Rechtschaffen, a sleep expert and a professor emeritus at the University of Chicago, told the New York Times in 2003:
It may be the biggest open question in biology. While we sleep, we do not procreate, protect or nurture our young or gather food.
Or in the words of William Dement, a pioneer in the field of sleep research and founder of Stanford University's Sleep Research Centre:
As far as I know, the only reason we need to sleep that is really, really solid is because we get sleepy.
We don’t know why we sleep, but we know we certainly can’t go without it.
In medieval China, death by sleep deprivation was considered the severest of punishments. Death would usually arrive in a little over two weeks and be accompanied by a descent into delusion, terror and madness. In more recent times scientific experiments on rats and puppies have shown that sleep deprivation is fatal. As far back as 1894, Russian scientist Marie de Manaceine started experimenting on puppies (clearly a cat lover!). When she deprived 10 puppies of sleep for four or five days it:
caused irreparable lesions in the organism and in spite of every care these [puppies] could not be saved. Complete absence of sleep during this period was fatal to puppies, in spite of the food taken during that time.
Interestingly, the exact cause of the fatalities was a mystery. The report stated that “no anatomical cause of death was identified”.
But sleep deprivation has serious consequences long before death. Of course, there is a difference between acute and chronic sleep deficiency. Short-term or acute symptoms may occur if we lose a night’s sleep, but most people make a full recovery in two or three days.
Chronic sleep deprivation happens when the sufferer does not make up their sleep debt, resulting in more serious physical and emotional symptoms.
Scientists now believe that long-term lack of sleep leads to depression, high blood pressure, weight gain, heart disease and overall mortality. Other listed or suspected effects include:
- Cognitive impairment
- Memory lapses or loss
- Impaired immune system
- Decreased reaction time
- Growth suppression
- Type 2 diabetes
- Symptoms like ADHD
- Breast, ovarian and prostate cancers
And if that were not enough, sleep disorders have been heavily correlated to heart attacks and strokes, car accidents and fatal injuries. Lack of sleep also has been found to have a major impact on our ability to regulate our weight.
The incidence of death from all causes goes up by 15% when we sleep five hours or less per night!
Six Hours is NOT Enough
Despite what many people claim, six hours of sleep a night is not enough to operate at our peak (or to stave off the effects of sleep deprivation).
Researchers at the University of California, San Francisco have discovered that some people have a gene that enables them to do well on six hours of sleep a night. This gene, however, is very rare, appearing in less than 3% of the population. For the other 97% of us, six hours is not enough (more on this later).
And the notion that a person can "catch up" on lost sleep on the weekend is also wrong.
Dr Steven Feinsilver, a pulmonologist and sleep specialist who directs the Center for Sleep Medicine at Mt. Sinai School of Medicine in New York City, states:
If you’re getting five hours of sleep Monday through Friday, by Friday, you owe yourself like, 10 or 12 hours of sleep. [But] it’s not quite that simple. What that means is that, in order for you to catch up on weekends, you’d have to sleep ridiculous hours. And nobody does. You’d have to sleep the seven, plus an extra 12.
Sleeping at weekends might relieve part of our ‘sleep debt’, but it won’t make up for the overall deficit. It will also likely affect our sleep-wake cycle, making it harder for us to go to sleep on Sunday night.
Signs That You’re Not Getting Enough
You (or your staff) may be sleep deprived if you:
- Need an alarm clock to wake up on time
- Keep hitting the snooze button
- Have a hard time getting out of bed in the morning
- Feel sluggish in the afternoon
- Get sleepy in meetings or warm rooms
- Get drowsy after heavy meals or when driving
- Need to nap to get through the day
- Fall asleep while watching TV or relaxing in the evening
- Feel the need to sleep in on weekends
- Fall asleep within five minutes of going to bed
How Much Sleep Do We Need?
To get the best from our staff and ourselves, we need to get our beauty sleep (yes, there’s evidence that sleep contributes to the health of our skin and our overall appearance as perceived by others). To understand how much sleep we need, we must turn to the sleep cycle.
When we sleep, we usually pass through four stages in the following order: stage 1, stage 2, stage 3 and REM. To do so takes an average of 90 minutes, with remarkably little variation from person to person.
Stage 1 (sleepiness) is a light sleep where we drift in and out and can be woken easily. Our eyes move slowly and muscle activity slows. (During this stage, many people experience sudden muscle contractions preceded by a sensation of falling.)
Stage 2 (light sleep) is marked by no eye movement and slower brain waves.
Stage 3 (deep sleep) is when our brain produces extremely slow brain waves (called delta waves) interspersed with faster waves which phase out as the stage progresses. It is difficult to wake someone from stage 3 sleep. There is no eye movement or muscle activity. (This is when some children experience bedwetting, sleepwalking or night terrors.)
REM (Rapid Eye Movement) sleep is characterised by rapid, irregular and shallow breathing and jerking eye movements. Interestingly, our limbs are paralysed during this phase, which is a good thing because this is when we dream. Brain waves during this phase are similar to when we are awake.
That is the sleep cycle. The important point about the cycle is that we need to have five complete 90-minute cycles per night to be properly rested. It’s where the old 'eight hours a night’ proverb comes from - fifteen minutes to nod off, fifteen minutes to wake up, and five complete sleep cycles in between.
Our brain naturally surfaces to wakefulness between cycles to run a quick check on our surroundings. It’s an obvious survival mechanism and it’s very easy to check in practice with the help of a bedside clock. It’s surprising how remarkably accurate and consistent the 90-minute cycle is.
Deep sleep seems to be the time our bodies renew and repair. When we finally get to bed after a period of sleep deprivation, we pass quickly through the lighter sleep stages into the deeper stages and spend a greater proportion of sleep time there – which suggests that deep sleep plays a large part in restoring alertness. Another interesting fact is that deep sleep is nearly absent in most people over the age of 65.
The first three sleep stages last about 65 minutes; REM lasts about 20 minutes (shorter in the first cycles, longer in the latter cycles each night) and is followed by our few minutes of semi-wakefulness.
The key to waking fresh in the morning is to wake naturally, at the end of our fifth cycle. (And if we won’t be able to get a full set of sleep cycles before we must get up, we should set our clock for a multiple of 90 minutes – plus a few minutes to nod off.)
Waking during a sleep cycle, instead of at the end, is what leaves us feeling groggy, hard to start and more tired than when we went to bed.
Getting Off to Sleep
There are some simple things we (and our staff) can do to improve sleep quality. It all begins with recognising the importance of sleep and that it’s not just something we ‘fit in’ at the end of the day.
- Enforce a caffeine curfew. Caffeine makes it harder to fall asleep, reduces our sleep by an average of one hour per night, and stops us dipping into the normal ranges of deep sleep. It even masks from us the difference in our sleep quality (see caffeine link in Resources). Stop consuming caffeine at least six hours before bedtime.
- Set a fixed bedtime. Help our biological clock by going to bed and getting up at the same time each day, every day.
- Develop a relaxing pre-bedtime ritual. Switch off the screens (TV too) 30 minutes before bed. Blue light from screens inhibits melatonin production, a vital ingredient for falling asleep and for regulating our sleep and wakefulness cycles. Reduce the overall level of light and start to relax by playing music or reading something that doesn’t require much effort (a novel is better than non-fiction).
- Keep electronic devices out of the bedroom. Our bedroom is our private sleep sanctuary. We shouldn't let other people invade via our smartphone. 🙂
- Lower the temperature. During sleep our bodies are meant to cool down. Studies have shown that external temperatures of 16 to 20 degrees Celsius trigger the body to release more melatonin. During REM sleep the brain’s temperature-regulating cells go to sleep too, which means that our body temperature becomes determined by the temperature of our bedroom. This is why trying to sleep in the heat is so miserable — the external temperature prevents our internal temperature from being where it needs to be for a deep sleep.
Of course, cutting noise (ear plugs?) and reducing light (eye mask?) are important too.
In fact, light plays a crucial role in keeping our circadian rhythms on schedule and maintaining our sleep/wake patterns (sleep problems affect a large number of blind people). We need to sleep when it's dark and be awake when it's light.
Too much food or alcohol before bed won’t help either!
Food for Thought…
- Long-term sleep deprivation is bad for our health in lots of ways
- Long-term sleep deprivation is hard to recognise in ourselves or others
- We need 7.5 hours sleep per night (5 x 1.5 hour cycles)
- There are things we can do to help us get to sleep and to sleep well
We can't be on hand to make sure that the staff coming in tomorrow (and the children!) all go to bed at a reasonable time. However, we do have a keen interest in everyone in the centre being well rested.
Discussing sleep in next week’s staff meeting (and family newsletter) might be worth thinking about.
Scientists are resoundingly confirming what our ancestors knew instinctively: that our sleep is not empty time. Sleep is a time of intense neurological activity—a rich time of renewal, memory consolidation, brain and neurochemical cleansing, and cognitive maintenance. Properly appraised, our sleeping time is as valuable a commodity as the time we are awake. In fact, getting the right amount of sleep enhances the quality of every minute we spend with our eyes open. - The Sleep Revolution, Arianna Huffington.
Can You Die From Sleep-Deprivation?
Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed
Blind often afflicted with rare sleep disorder
The Biology of Sleep
Arianna Huffington: Getting Enough Sleep Is Non-Negotiable
How Much Sleep Do We Really Need?
Are You Getting Enough Sleep?
How to Spend the Last 10 Minutes of Your Day
The Science of Sleep: Regulating Emotions and the Twenty-four Hour Mind