The ongoing COVID-19 pandemic has consequences beyond the viral disease with its morbidity and mortality, as it impacts households, financial security and causes anxiety and sleeplessness. Regular daily activities are replaced by a new and mostly damaging daily routines for people confined to their homes. Sleep gets a hit and stress increases.
Sleep is essential for performance, and the “sleep debt” accumulating during a time of crisis must be paid back one way or another, or the body and mind will suffer. Usually, in the efforts to survive a crisis, the body needs as much sleep as possible, but the situation and logistics usually do not allow it. In the unique situation of COVID-19, under quarantine, sleep opportunities seem higher, but what makes a big difference is a clear downgrade in the quality of sleep we get due to the sudden life changes, and related fears and anxiety. Our minds are busy as countries are on lockdown, many are losing their jobs, the economy is slowing down, a disease without a known remedy is spreading fast and kills increasing numbers of people deemed to die in isolation. The fear of the unknown, the ceaseless flow of contradictory news, messaging and statistics indicating apocalyptical outcomes, the loss of daily routines and the mandatory social distancing have devastating results: loneliness, anxiety, gloomy mood and sleep loss.
Yet sleep has never been more important! Indeed, sleep is a forgotten natural remedy necessary for our immune system to fight infection, for our bodies to recover after a disease, and for our minds and souls to deal with stressful events.
Studies show that low sleep efficiency and short sleep duration in the weeks preceding exposure to a rhinovirus and other infectious factors are associated with increased disease risk. Lack of sleep can affect recovery. Sleep improvement is recognized to have a positive effect on co-existing mood disorders.
To understand the nature of sleep, it’s important to understand the difference between sleep and wakefulness, as well as the presence of sleep stages. Being awake is a state of consciousness accompanied by heightened perception, realistic thinking, environmental responsiveness and physical activity. In contrast, sleep is a behavioral state of decreased perception, relatively low responsiveness to the environment and physical inactivity (or rest).
A quiescent body is the most obvious characteristic of sleep, but the brain remains active at varying levels while regulating sleep and performing vital tasks. Indeed, during certain phases of sleep, the brain is more active than during wakefulness.
There are two fundamental sleep states: REM (rapid eye movement) sleep and non-REM sleep. Each is regulated by a different part of the brain; and the difference between those states is as profound as the difference between sleep and wakefulness. REM sleep is regulated from the brainstem, whereas non-REM sleep is regulated from higher brain centers.
As a practical matter, scientists differentiate between three states (wakefulness, non-REM sleep and REM sleep) by measuring
· electrical activity in the brain via electroencephalography (EEG)
· eye movements via electrooculography (EOG)
· muscle activity via electromyography (EMG)
The following are more precise descriptions of the behavioral and physiological changes across these states.
Awaking state may be quiet, physically active or mental active.
Non-REM sleep has three stages (1, 2 and 3) which are differentiated by their degrees of sensory and motor disconnects from the environment. The magnitude of those disconnects is otherwise known as sleep depth. (Stage 3 is the deepest). Increasing depth means
· slowing, mostly homogenous electrical activity in the brain
· decreased slow-rolling eye movements (ceasing completely in stages 2 and 3)
· decreased muscle activity (though movement is always possible)
· decreased respiration and heart rate, but increasing regularity
· decreased oxygen consumption
· growth hormone secretion (stage 3 or deep sleep)
· decreased sensitivity of pain receptors
· stable body temperature control
· realistic and analytical thought processes (similar to wakefulness)
REM sleep is characterized by varying levels of sensory disconnection from the environment and an inability to move. The important characteristics are
· rapid and heterogeneous electrical activity within the brain (similar to that of wakefulness)
· inhibition of voluntary muscles leading to near-paralysis with some irregular twitches
· rapid eye movements similar to those of wakefulness
· decreased control of body temperature
· faster and irregular heart rate and respiration (relative to non-REM sleep)
· penile tumescence
· increased oxygen consumption
· hyper-associative dreaming with bizarre thoughts
Although the three states (wakefulness, non-REM sleep and REM sleep) have very distinct physiological characteristics, there may be overlap under certain circumstances. For example, sleepwalking occurs mostly during non-REM deep sleep while the behavior looks like movements occurring usually during.
At any given time, a human being is in one of the 3 stages: wakefulness, REM sleep and non-REM sleep. On average, adults are awake for 2/3 of the 24-hour day and asleep for the other 1/3. When sleeping, the relative proportions of sleep states are roughly
· 50% in light non-REM sleep
· 20-25% in deep non-REM sleep
· 20-25% in REM sleep
An amazing statistic: In a 90-year lifespan, a person will probably have slept for 30 years and will have spent 10 years dreaming!