I have sleep issues. My interest in sleep began as a teenager, pulling the books on dream analysis off my psychiatrist stepfather's shelf... symbolism, Freud, and all that. We used to analyze my dreams together sometimes. He wasn't a huge believer in all that (nor was I, necessarily but I was exploring), but what he did find interesting was how often I dreamt... and remembered them. He said he hardly ever did (which was fine with him.) Even to this day, I barely go a night without dreaming, but I certainly long for those deep slumbers, where I slept well into the day (if my parents weren't feeling 'parental'), light and noise, or not. (FAQ: Teens need ~ 8-10 hrs/n to function best; 9.25, by most studies.)
These days I'm much more interested in sleep and wish I could stop dreaming all together (as I somewhat blame it for my messed up sleep cycles.) My dreams are most often literal, and I now believe simply the mind's way of categorizing and filing the daily detritus (and sometimes important events) of the day. For me, it's as straight-forward as see-something-dream-about-it. But sleep, sleep is so much more integral... and as I age, less efficient, evasive. One of my first questions on GAG was about insomnia. (No need to give more advice on that, thanks. It's a complicated topic to unravel and trust me, I've put the time in.)
Recently I did a bit more research, looking for info specifically on sleep cycles (as I suspect this is now my new main issue), and so read another article, an interview, and thought I would share some of the perhaps lesser-known takeaways with you, fyi.
Why is Sleep Essential?
1. To save energy
2. To help cells recover
3. To help process & understand our environment (aka “the synaptic homeostasis hypothesis”)
The 24-hr Circadian Rhythm
Every living organism is responsive to a circadian rhythm largely dictated by sunlight. Even bacteria in the ocean differentiate sunlight from darkness. The photo receptors in eyes pick-up on sunlight, controlling the release of melatonin and other neurotransmitters that dictate energy levels throughout the day. This is chronobiology.
Peak awakeness occurs during the morning. After lunch there is a glucose spike, especially if after a heavy lunch. That glucose spike combined with a circadian dip creates a period of fatigue between ~ 2-4pm. Then there is another spike in alertness right before dinner, before getting tired (hopefully around bedtime.) That’s the 24-hour circadian rhythm. (And note that it isn’t fixed. It’s changeable.)
The environmental cues we react to and that impact our circadian rhythm are called zeitgebers (bless the Germans.) The biggest zeitgeber is sunlight. Others are: the timing of meals, exercise, having a consistent bedtime; though a larger issue is the amount of time we now spend indoors. Without naturally-occurring sunlight, we become easily entrenched in non-natural rhythm.
The 3 Sleep Cycles
The stages of sleep are: light sleep > deep sleep > light sleep > REM... and repeat.
* The time during which new information is integrated into long-term understanding of the world.
* The more sleep, the more light sleep you have.
* Long-burst brainwaves that are called delta waves.
* Human growth hormone, cell-recovery, and the ability to process new information are associated with deep sleep.
* What deep sleep does is all the neural processing.
* The first sleep cycle is very heavy in deep sleep.
* When sleep-deprived, there is increased deep sleep.
* Rapid-eye-movement sleep.
* Brainwaves are functioning similarly to waking life.
* REM sleep is the processing of information.
* The body is paralyzed.
* Thermo-regulation is lost, meaning if it’s hot in the environment, the body gets hot.
* Although most dreams do take place during REM sleep, more recent research has shown dreams can occur during any sleep stage.
Why Do We Wake Up Tired & Groggy?
When you wake up, you are in a state of 'sleep inertia.' It can last as long as 2 hrs. This is the cause for that pesky groggy feeling (and if sleep- deprived, it’s even worse.)
The causal mechanism is a lack of cerebral blood flow. It takes time for the brain to kick back into gear. This is accompanied by a gradual increase in brain blood flow to normal levels. It begins with the primitive parts of the brain (the brainstem and thalmus) and then spreads to anterior cortical regions after ~ 15 min. During this time basic cognitive tasks are impacted.
What makes it worse? Waking up at the wrong time, while in deep sleep creates worse inertia, making you feel more tired.
The right way to wake up is gradually. If sleeping a healthy amount, you’re getting almost no deep sleep by the end of the sleep, as the amount of deep sleep reduces over the course of the night. This means you’re less likely to wake up in deep sleep if you’re well rested, and therefore less likely to feel groggy.
Being a 'Morning Person' or 'Night Person' is Dictated by Your Genes
It is not a myth (or an excuse.) You do have genes that dictate being a morning or evening person. If you’re a morning person, it's referred to as a lark. If you’re a night person, a night owl. Your genes give you a greater proclivity to being one or the other. As well, some people have genes that make them advantageously very flexible (lucky you. You are fortunate, and rare.)
The History of Sleep & How Society is Changing Our Relationship with Sleep
There is some evidence that we used to go to bed when the sun went down, then later wake up for a bit, putter around, make sure there's no lions about, etc., then go back to sleep. So waking up in the middle of the night has been a part of civilization throughout history. Gallup, Inc. (analytics) has reported that over the past 50 years, we’re sleeping 1 hr less/night than we did in the 1950s. That's a lot. Much of it has to do with TV and mobile phones; add to that the lack of work/life balance. Fewer people continue to have a 9-5 schedule. This is especially true for independent freelance, contract, and creative jobs. Work used to be very manual, but as jobs are becoming more and more cognitive, caring for cognition is going to become increasingly important for proper functioning.
Tips for Improving Sleep
The most important factor conducive to productivity is rest. Often times people think they can fight and push through the fatigue, but sleep provides this most efficiently. It also stores newly-learned skills into long-term memory, with each sleep cycle. Here's another benefit: When transitioning in and out of sleep, the brain produces theta waves, which help you think more divergently. This is why after waking up, you are sometimes able to solve that intractable problem that you could not earlier in the day.
We need stimulus control - a cold, quiet environment, with no light, and no stress. Oh, and save the bedroom for sleep and sex.
Sound: Focus on sound. Quiet environments improve sleep quality, so blocking out noises is key. Even an A/C unit turning on will wake up the brain. If you can't stop noise, try gently drowning it out. Water, frogs or birds, anyone?
Temperature: Sleep experts say that a cool room, ~ 65°F/18°C is optimal. Everyone has different natural body temperatures, and men usually run hotter than women (likely due to higher muscle mass.) This can be a serious challenge, trying to create an environment with a partner with a different body temperature. You must do everything you can to find an acceptable balance for both, whether that means A/C on, heat off or low, window open, fewer blankets on the bed, or custom 2-sided bedding (and if in doubt, cooler wins - the science is with them.)
Light: No light. Not even blue light (or, especially not blue light.) Many studies confirm this. Options: Place cell phone in another room (out of sight, sort of out of mind), lower the screen brightness, use an auto-timed warming filter to remove blue and add red; Install blackout window treatments; Use a sleep mask.
Wearable Tech & Trackers
Ex: Fitbit. Fitbit is pretty accurate in measuring when you’re asleep and when you’re awake, but when it comes to measuring sleep stages, basically any device that measures heart rate (like the Apple Watch) is totally inaccurate. Why? Because they don’t sample at the frequency necessary to get an accurate reading on sleep stages. Fitbits can also create problems with all their tracking - causing you to stress out about the fact you think you’re not getting enough deep sleep, basing this on the false information of it not having accurately measured the sleep stages.
So, How Much Sleep Do We Need?
8.5 is the new 8. The standard in the literature is that healthy sleepers spend more than 90% of the time in bed asleep, so if you’re in bed for 8 hrs, a healthy sleeper might actually sleep for only about 7.2 hrs. It’s possible to have your sleep a little broken up, but getting 8 hrs is crucial. And in order to get 8 hrs, you need to be in bed for 8.5 hrs.
Portions transposed and edited from an interview by Georgia Frances King with sleep scientist Daniel Gartenberg.
My prior sleep question (Lots of advice for insomniacs here)