If you’re on the older side and find yourself popping hideously awake in the middle of the night or far-too-early morn, here’s your line for the next time it happens: “Oh, that darned ventrolateral preoptic nucleus of mine! How I miss my old galanin!”
Researchers have just reported in the journal Brain that they’ve found a group of neurons — in the aforementioned nucleus – that function as a kind of “sleep switch,” and whose degeneration over the years is looking very much like the cause of age-related sleep loss. It’s also looking pivotal in the insomnia that often causes nocturnal wandering in people with Alzheimer’s disease.
“This is the first time that anyone has ever been able to show in humans that there is a distinct group of nerve cells in the brain that’s critical for allowing you to sleep,” said the paper’s senior author, Dr. Clifford Saper, chair of neurology at Beth Israel Deaconess Medical Center and professor of neurology at Harvard Medical School.
You may well be wondering exhaustedly how soon this insight — based on the post-mortem analysis of 45 human brains — will lead to better sleeping pills for older folks. I asked Dr. Saper that, too. No promises with timeframes at this point, but he does see the prospect for better-targeted sleeping pills for seniors, with fewer side effects like Ambien’s balance-related problems.
Our conversation, lightly edited:
Can this group of neurons actually explain the lion’s share of sleep problems that older people and people with Alzheimer’s disease have?
It really can. Let me give you a little background. We discovered this cell group in the brains of rats in 1996. We found that there’s a group of of nerve cells in a part of the brain called the hypothalamus that fire when animals are asleep. And we later found that if you eliminate those nerve cells, that animals lose up to 50 percent of all their sleep time, and the remaining sleep is fragmented. They can’t sleep for long bouts at a time; they keep waking up all the time.
At that time, we weren’t sure whether this would be the same in other species. So we looked at the brains of half a dozen other species — of mice and cats and monkeys — and we found that all of them have this cell group and that the cells were active during sleep in all of them. In every species we looked at, this same cell group had a particular neurotransmitter in it, called galanin.
I’ve never heard of that neurotransmitter before… Continue reading