Sleep is an integral part of our life and, as research shows, it is incredibly complex. The brain generates two distinct types of sleep: slow wave sleep (SWS), known as deep sleep, and rapid eye movement (REM), also called dream sleep. Most of the sleep we do is of the SWS variety, characterized by large, slow brain waves, relaxed muscles, and slow, deep breathing, which can help the brain and body recover after a long day.
Sleep helps the brain learn and stay flexible
Scientists monitored participants’ brain activity – their motor cortex, in particular – throughout the study. The team – led by scientists based in Switzerland – found that restless deep sleep resulted in noticeably reduced learning efficiency. The researchers explained that their results depended on the brain’s synapses and their roles in learning. Synapses are microscopic connections between neurons that, along with chemicals in the brain, or neurotransmitters, facilitate the passage of electrical impulses from one neuron to another. During the day, synapses light up in response to stimuli the brain receives from the environment. But during sleep, the activity of these synapses returns to normal. Without this restorative period, they stay excited at their peak of activity for too long. This interferes with the neuroplasticity of the brain, that is, its ability to rewire itself and create new connections between neurons. Neuroplasticity allows the brain to learn new skills, change and adapt to stimuli in its environment, and ultimately learn new things.
Your body’s built-in sleep controls
According to Researcher, there are two main processes that regulate sleep:
- circadian rhythms
- sleep drive
Circadian rhythms are controlled by a biological clock located in the brain. A key function of this clock is to respond to light signals, increase the production of the hormone melatonin at night, and then turn it off when it senses light. People with total blindness often have trouble sleeping because they are unable to detect and respond to these light signals. The sleep rush also plays a key role: your body craves sleep, just as it craves food. Throughout the day, your desire to sleep increases, and when it reaches a certain point, you need to sleep. A major difference between sleep and hunger: Your body can’t force you to eat when you’re hungry, but when you’re tired, it can put you to sleep, even if you’re in a meeting or driving a car. When you’re exhausted, your body is even able to engage in episodes of one or two seconds of micro-sleep while your eyes are open. Taking a nap more than 30 minutes later in the day can disrupt your night’s sleep by decreasing your body’s sleep.
When we fall asleep, the brain doesn’t just switch off, as the popular phrase “like a light” suggests. Instead, a series of highly orchestrated events put the brain to sleep in stages. Technically, sleep begins in the areas of the brain that produce SWS. Scientists now have concrete evidence that two groups of cells – the ventrolateral preoptic nucleus in the hypothalamus and the parafacial zone in the brainstem – are involved in inducing SWS. When these cells light up, it triggers a loss of consciousness.