We all know that lack of sleep reduces alertness and leads to careless mistakes and promotes irritability. Research suggests that these moments of bewilderment are caused by a cessation of the electrical activity of certain neurons, causing a local “micro-sleep” which alters certain cerebral functions. Like what you can literally sleep standing up!
With nearly 50% of the population sleeping less than seven hours a night during the week, lack of sleep has become a major problem in industrialized societies over the past few decades. This is a much more serious phenomenon than one might think, as more and more studies indicate that this lack of sleep can promote the development of a range of serious chronic diseases, ranging from heart disease to certain types of cancer.
Not to mention that the lack of sleep has repercussions on the general functioning of the tired person: distraction, reduced alertness at the wheel, irritability, lack of attention at work or towards loved ones, to name a few. one. But why does the brain have such a hard time coping with lack of sleep?
Brain activity consumes 20% of all energy in the body
Neurons are cells that have the property of being activated by variations in electrical potential and of using these variations to propagate information by connecting to other neurons. Like all cells in the body, neurons cannot be constantly active and must rest to regenerate their energy sources. Thinking is a demanding act that consumes almost 20% of all the body’s energy! The electrical activity of neurons therefore varies enormously depending on whether the brain is in a state of wakefulness or sleep: during wakefulness, most neurons are in an active state, capable of propagating an electric current.
During sleep, it is exactly the opposite, most neurons being in a state of rest, electrically inactive. This moment of rest associated with sleep is also a “signature” of the brain, an electrical activity profile easily measured using an electroencephalogram (EEG).
Lack of sleep: the brain unplugs you to recover
Although sleep is generally considered to be a global process that affects the whole brain, certain observations suggest that it could also involve certain specific brain areas. For example, some animals like birds and dolphins have the ability to put half of their brains to sleep while the other half stays awake (hence the phrase “sleep with one eye open”! ). Recent work suggests that a similar phenomenon could occur when the brain is subjected to a lack of sleep. The researchers observed that when model animals were forced to remain awake for long periods, neurons in certain regions of the brain temporarily ceased to function.
The longer the sleep deprivation, the more frequent this stoppage of function became and considerably impaired the animals’ ability to perform certain tasks that were normally easy for them. In other words, when the brain is tired, the work overload forces certain neurons to “sleep” and this local micro-sleep thereby leads to a reduction in the efficiency of the performances that depend on these neurons. If you’re tired and having trouble performing a routine task, you’re probably a victim of those napping neurons!
We spend a third of our life sleeping.
Like all the organs of the body, the brain must replenish its energy to be able to remain in a maximum state of functioning. Given that all of our physiological functions, and more particularly our cognitive functions, are strictly dependent on an alert brain, it is not surprising that we spend almost a third of our lives sleeping! Taking care of your health obviously means sleeping as much as your body needs.
At a time when we pride ourselves on hyper-performance, sleep is seen by some as a sign of laziness; it is good to remember that sleeping is an essential biological activity to maintain the functions of the organ that defines us as a species: our brain. Our quality of life depends on adequate sleep.
Vyazovskiy VV et al. Local sleep in awake rats. Nature.