Matthew Walker — a sleep scientist, debunks myths of sleep (and dreams) and explains in various areas and great detail on the neurology and sociology aspects of sleep in this book, Why We Sleep. Hopefully, you will head to bed after reading this piece.
Background
Before we jump straight into the numerous interesting studies, let’s introduce the mechanics of sleep. Two factors and their balance regulate your sleep and wakefulness.
- A 24-hour clock within our brain called the circadian rhythm. You feel alert during the day and tired at night. The rhythm is constant and not affected by factors.
- Adenosine, a chemical substance, builds up in your brain and creates a ‘sleep pressure’. The longer you stay awake, the more it accumulates, and the sleepier you feel.
Within sleep, there are two types — NREM and REM. NREM sleep helps to store and strengthen new facts and skills while REM sleep helps to integrate connections between facts and skills, and linking them with your past experiences to update your mental model of how the world works. Your dreams also occur during your REM sleep. You need a good amount of NREM and REM sleep for the healthy functioning of your body and brain.
I will be picking a couple of things to talk about: the idea of night owls versus early birds, caffeine, diet, and productivity, regarding this huge topic of sleep.
It’s only 1 AM
Our world seems to celebrate the early birds — You should sleep early and wake up early — and casually labels the nocturnal night owls as lazy —Stop sleeping in till so late. A night owl usually wakes up later in the day, because they did not sleep till the early AM. People (usually the early birds) assume that this sleep cycle is a choice or preference and if the night owls will it, they can wake up early as well. The truth is these night owls are not owls by choice. They are wired as such due to their genetics.
Looking at the circadian rhythms of both an early bird and a night owl, we can observe the distinct differences. The peak of the early bird’s rhythm starts earlier than a night owl’s. Remember how we mentioned that these circadian rhythms are constant and not affected by external factors? This is simply a matter of DNA at play.
This constant circadian rhythm can change within a person’s lifetime. An 8-year old child would be asleep at 9 PM due to the circadian rhythm resembling that of an early bird’s. But at 17-years old, the same individual’s circadian cycle will undergo a dramatic shift forward (resembling a night owl’s), causing 9 PM to be the peak wakefulness for the teenager instead. My mother was probably frustrated as to why I just couldn’t sleep early back then.
The unfortunate thing for these night owls is the unleveled playing field of our society’s schedules. Jobs and schools have early starting times. This punishes the owls and favors the early birds as the standard schedules force the owls into an unnatural sleep-wake rhythm. As a result, they often are not performing at their best in the morning and are more chronically sleep-deprived.
Espresso to go, please
If you don’t know how the caffeine in coffee keeps you awake, this is a short and cute video. In short, caffeine competes with adenosine (the one that causes sleep pressure) by binding to the same receptors, effectively blocking the sleepiness signal that is normally communicated to the brain. Caffeine causes you to feel alert and awake by building up a wall to hold back the high levels of accumulated adenosine. Eventually, when your liver dismantles that wall, you will feel the backlash. Unless you consume even more caffeine, (which can create a dependency cycle), it is difficult to stay awake.
The problem with caffeine on sleep is due to its persistence in your system. The ‘half-life’, or time required for your body to remove 50% of a drug’s concentration, of caffeine is 5–7 hours. This means that to fully overcome a single dose of caffeine, it can take some people half a day. Of course, this depends on the efficiency of your enzyme in your liver that breaks down the caffeine. Some people can drink coffee without experiencing the effects. One point to note: the older we get, the longer it takes our brain and body to remove caffeine, so we become more sensitive to the sleep-disrupting influence of caffeine.
I am a Cookie Monster
If you have an uncontrollable habit of reaching out for that cookie, perhaps you want to consider how you have been sleeping.
2 hormones control our appetite: leptin (feeling of fullness) and ghrelin (desire to eat). When you have inadequate sleep, your leptin concentration decreases, and ghrelin increases. This means that you feel less satisfied after eating and you want to eat more. Your endocannabinoids also increase, which stimulates your appetite and desire to snack. Basically a lose-lose situation.
What we choose to eat when we are sleep-deprived is different. Running on 5–6 hours of sleep, our cravings for sweets, carbohydrate-rich food, and salty snacks increases by 30–40%; protein-rich food, dairy, and fatty food cravings increases by 10–15%. This is due to the silencing of our pre-frontal cortex and the amplification of our primal deep-brain structures when we lack sleep. Our pre-frontal cortex is responsible for careful judgments and controlled decision-making whereas our primal deep-brain structures drive motivations and desires. Hence, when we lack sleep, we automatically see high-calorie food as more desirable. But when we sleep, the higher-order brain regions can help us to rein in our cravings.
For those watching their waist-lines, note that sleep deprivation can cause you to have less energy and increases your probability of adopting a potato lifestyle. On top of that, when we are sleep-deprived, 70% of weight loss comes from muscles vs 50% weight loss from fats when we have sufficient sleep. Our body doesn’t want to give up fats with insufficient sleep.
(Un)productivity
After merely 10 days of 7 hours of sleep, our brain is similar to us not sleeping for 24 full hours. Even subsequent 3 full nights of recovery sleep are insufficient to restore our brain performance back to normal levels. Sleep isn’t like a credit system where we can clock more hours on one day and less on another and hoping that it will balance out. The brain can never recover all the sleep it has been deprived of and it cannot accurately detect how sleep-deprived it is when sleep-deprived. But how does that translate to productivity, especially in the workplace?
Let me paint the picture of a negative feedback loop. When I have an insufficient amount of sleep, I work less productively and this causes me to work longer hours to finish a task. Longer hours mean that I need to sacrifice sleep to finish it and thus deepening my sleep debt. I also choose less challenging problems to solve, opt for an easy way out, and generate lesser creative solutions. I begin to dislike my job because of the mood-depressing influence of sleep deficiency (this reminded me of my Sims when they were sleep-deprived). My frontal lobe, which is critical for self-control, cannot effectively rein in emotional impulses due to sleep deprivation. I become more emotionally volatile and rash in my choices. I’ve become the textbook employee that no one likes.
The scary part from studies has shown that participants who are sleep-deprived don’t perceive themselves as less effective and are unaware of their poorer work effort and performance. This ‘sleep-is-for-the-weak’ mentality in any work environment is evidently wrong and needs to stop.
Sound sleep is sound business.
Final Remarks
Right now, we see a rise in using analytics to track sleep. The author also threw in the possible shift towards predict-analytics where we can utilize these data to make health predictions (when is the best time to take that flu jab for maximum effectiveness), create better devices to wake us up (alarm clock and snooze button actually inflict damages on your heart and nervous system) and propose policy changes such as insurance premiums based on your sleep schedule and flexible school/work timings. The possibilities are endless and I am excited to see innovations in this area!