By Professor Grant Schofield
So, let’s just take it from the start. Before a baby is born, when you’ll feel it kicking around and moving – which is all very exciting – interestingly, the baby is probably asleep and dreaming. They haven’t developed the paralysis of dreaming yet. The fetus spends about 20 hours a day sleeping, because sleeping is so crucial for brain development in that stage.
If children before birth are deprived of non-REM and REM sleep, they will be deprived of crucial aspects of development. One of the most important reasons for avoiding alcohol during pregnancy, may be that it affects the non-REM and REM sleep of the fetus. And when you deprive them of that, it holds back brain development. This has been shown in animal studies with rats.
After the baby is born, it needs to sleep a fair bit. It hasn’t got its normal melatonin and circadian cycle in place yet. That takes up to six months to develop. When fully developed, you’ll get more of the day/night sleeping pattern. But before then, the baby is still spending much of its time in sleep, taking in and processing information from the world, and that’s why it’s so important.
Through teenage years, interestingly, we see an increase, not in dream sleep, but an increase in non-REM or deep sleep. One of the reasons for this may be a pruning, refining and trimming down of the brain to be a refined, particular and specialised organ to suit exactly the environment that the teenager is in.
Through adulthood there is, in general, a decrease in the quality of sleep. While the light sleep and the dream sleep stay more or less the same, with a slight decrease, the non-REM sleep plummets as we grow older.
“For some reason, one of the most important parts of sleep, the deep non-REM sleep, decreases in older age.”
We’re not exactly sure why that is, but it does happen. It doesn’t mean we need less sleep, in fact we may need more sleep. We just don’t fully understand it.