Given that around one-third of our lives is spent sleeping, sleep must be considered for effective time management. I believe it’s a mistake to regard sleeping as wasted time and to work to keep the time we sleep to a minimum. I have a good friend who is quite proud to have gotten it down to four hours per night. I have never been able to understand why this is desirable. For me, sleeping is one of my favorite activities. Apart from being refreshing, I enjoy dreaming. We are able to slip the bounds of reality when we dream.
Levitin in his book The Organized Mind: Thinking Straight in the Age of Information Overload notes other reasons sleep is important. Newly acquired memories are initially unstable and require a process of neural strengthening to become resistant to interference and accessible to us for retrieval. Usually there are a variety of ways that an event can be contextualized. The brain has to toss and turn and analyze the experience after it happens, extracting and sorting information in complex ways.
Recent research has given us a better understanding of the different processes that are accomplished during distinct phases of sleep. New experiences become integrated into a more generalized and hierarchical representation of the outside world. Memory consolidation fine tunes the neural circuits that first encountered the new experience. It has been argued that this occurs when we sleep because otherwise those circuits might be confused with an actually occurring experience. Moreover, all this consolidation does not occur during a single night. Rather, it unfolds over several sequential nights. Sleep that is disrupted even two or three days after an experience can disrupt our memories of it months or years later. Mathew Walker (from UC Berkeley) and Robert Stickgold (frm Harvard Medical School) notes three distinct kinds of information that occur during sleep.
The first is unitization, the combining of discrete elements or chunks of an experience into a unified concept. The second kind of information processing that takes place during sleep is assimilation. The brain integrates new information into the existing network structure of other items in memory. The third process is abstraction where hidden rules are discovered and entered into memory. Across a range of inferences involving not only language but mathematics, logic problems, and spatial reasoning, sleep enhances the formation and understanding of abstract relations to the extent that people often wake having solved a problem that was unsolvable the night before. Levitin writes that this might be part of the reason why young children just learning language sleep so much.
This kind of information consolidation happens all the time, but it happens more intensely for tasks in which we are intensely engaged. If you struggle with a problem for an hour or more during the day in which you have invested your focus, energy, and emotions, the it is ripe for replay and elaboration during sleep.
Sleep is also necessary for cellular housekeeping. Specific metabolic processes in the glymphatic system clear neural pathways of potentially toxic waste products that are produced during waking thought.
Parts of the brain sleep while others do not. Sometimes we are either half-asleep or sleeping only lightly. Sometimes people experience a brain freeze being unable to momentarily to remember something obvious. Should we find ourselves doing something silly, such as putting orange juice on cereal, it might be that part of the brain is asleep.
Levitin likens the sleep-wake cycle to a thermostat. Sleep is governed by neural switches that follow a homeostatic process that are influenced by our circadian rhythm, food intake, blood sugar level, condition of the immune system, stress, sunlight, and darkness. When our homeostats increase above a certain point, it triggers the release of neurohormones that induce sleep. When the homeostat decreases below a certain point, a separate set of neurohormones are released to induce wakefulness.
Our current 6 to 8 hour followed by a 16-18 hour sleep cycle is relatively new according to Levitin. He writes that for most of human history, our ancestors engaged in two rounds of sleep, called segmented or bimodal sleep, in addition to an afternoon nap. The first round of sleep would occur for four or five hours after dinner, followed by an awake period of one of more hours in the middle of the night, followed by a second period of four or five hours sleep. He notes that bimodal sleep appears to be a biological norm that was subverted by the invention of artificial light.. He writes that there is scientific evidence that the bimodal sleep plus nap regime is healthier and promotes greater life satisfaction and efficiency.
Admittedly, it would be difficult for most of us to be able to accommodate this bimodal sleep regime. Do what works for you and fits into your requirements. Do not overlook the beneficial effects of naps, even very short ones. And stay away from sleep medications that can do more harm than good. Should you have difficulty falling asleep, the worst thing you can do is to get upset about it. Relax. Try meditating on a word or phrase. If you have difficulty attending to the phrase, just relax and gently bring your attention back to meditating. If you are having pleasant thoughts or memories, just go with the flow. Remember that parts of the brain might be sleeping while other parts remain awake, so don’t panic. Be patient. You might be getting more sleep that you think you are getting.
In closing, Levitin notes that sleep deprivation is estimated to cost US. businesses more than $150 billion a year in absences, accidents, and lost productivity It’s also associated with increased risk for heart disease, obesity, stroke, and cancer. So sleep is important. Don’t shortchange yourself.. If you have a chronic problem sleeping, seek professional help.