The importance of sleep
Sufficient and restful night sleep is absolutely important for us humans. Sleep researchers have been investigating why and how our brain regenerates during sleep for decades. Nightly sleep consists of different, alternating sleep phases, which can be represented differently by EEG waves, whereby different deep sleep phases differ from phases of lighter sleep.
Sleep changes in the course of life
Both the amount of sleep and the distribution of sleep phases change with age: infants still need about three times as much sleep as adults and 75% of their sleep consists of the so-called REM deep sleep phases, compared to 25% for adults. The maturation of the brain in particular seems to be an important reason for the changed sleep needs and proportions.
Learning in sleep
Learning, i.e. storing new knowledge in the long-term memory of the brain, takes place in the REM sleep phases, as we know today. Therefore it is absolutely essential for the developing brain as well as for the brain of adults that the different sleep phases are completed in their duration and quality. Sleep apnea is also an issue that affects the quality and quantity of sleep and should be taken into account.
However, knowledge is not actively stored in the hippocampus during sleep, but synapses are regenerated and degradation of the ß-amyloid occurs. Studies in rats show that prevention of REM sleep phases blocks the formation of new nerve cells in the hippocampus.(Guzman-Marin, R. et al.: “Rapid eye movementsleep derivation contributes to reduction of neurogenesis….of the adult rat” Sleep V. 31, 2008…).
The extracellular space between the brain cells is widened during sleep and is increasingly flushed by calcium and magnesium ions. This seems to have a cleaning effect on the brain. (Dale Bredeson: Die Alzheimer-Revolution, S.157)
Factors influencing REM sleep
Some drugs and also alcohol cause changes in sleep phases and fewer phases of REM sleep, which also causes a deterioration of regeneration and re-formation of nerve cells. Sleep apnea is also a problem that affects the quality and quantity of sleep and should be considered.
How much sleep do we need?
The opinions on this topic differ and lie between 7 and 10 hours per night. It is important to bear in mind that we are individuals and that the required sleeping time certainly varies from person to person. But if you feel as if you are wheeled out in the morning and not recovered, then either your sleep duration or the sleep quality is not right for you.
Things or activities turn night into day
- Bright light, especially artificial light with a high blue component (screens, smartphones, tablets, cheap LEDs, certain fluorescent tubes)
- Night work
- Not able to “switch off”