16 replies to this topic

[stephen_b]

Maybe the solution is not to sleep?

http://physorg.com/news114358662.html.

In order to test whether melatonin was involved in inhibiting nighttime learning and memory formation, they treated the zebrafish during the day with this hormone to see how the fish performed. Interestingly, melatonin failed to affect learning, but dramatically inhibited the formation of new memories, with the melatonin-treated fish resembling fish trained during the night in a test for 24-hour memory.
...
Next, with the pineal gland being the primary source of melatonin in fish and in people, Roman’s student Oliver Rawashdeh removed this gland from the fish and found they could now form memories at high levels even during the night. Removing this melatonin-producing gland allowed the researchers to alleviate the hormone’s negative side effects, further demonstrating that melatonin inhibits the formation of new memories during the night.

With these findings, Roman hopes to be able to retain the beneficial effects of melatonin’s antioxidant properties. Such benefits include fighting free radical damage to slow some forms of neurodegeneration, such as in Parkinson’s and Alzheimer’s diseases, and stopping DNA damage, which has potential to act as a preventative against cancer. And, since the positive antioxidant effect is direct and independent of receptor signaling, there is hope that removing the melatonin receptor signaling will combat only this hormone’s negative effects on cognitive function. 

But, do I need to form memories at night when I should be sleeping (my thoughts go back to those all-nighters in college)? Maybe it's beneficial not to.

Stephen

[zoolander]

I've been taking melatonin for the last 7 years and people comment on my memory. My memory is pretty good but it always blows me away when people comment on my memory, which is quite often.

So perhaps we better wait until the in vivo human studies before we become overly concerned about melatonin hurting memory formation

[stephen_b]

Here though I'm talking about the memory formed during the night when melatonin is active.

There's an interesting article in the New York Times magazine that says that

Most sleeping pills are known to block the formation of memories during their use, creating amnesia.

.
It goes on to say that a night of lousy sleep, where you toss and turn, is not remembered if you take a sleeping pill, accounting for the feeling that sleeping pills "create incommensurate feelings of having slept so well".

Some pill manufacturers disagree though.

Stephen

[zoolander]

There's an interesting article in the New York Times magazine that says that.....

Most sleeping pills are known to block the formation of memories during their use, creating amnesia.

Melatonin is not a sleeping pill. That is a huge misconception. You cannot compared melatonin with sleeping pills because melatonin simple increases the level of endogeous melatonin that stimulates a feeling of tiredness that subsequently helps you fall asleep. Sleeping pills, most of them, hit you on the head will a sledgehammer until you are unconscious. On top of this they are extremely addictive which Melatonin is not

[stephen_b]

I am not implying that melatonin is a sleeping pill, so while it may be a huge misconception, it's not my misconception. I thought that the similarity of effect on memory formation between melatonin and sleeping pills interesting, that's all.

Other than more vivid dreams, I have not noticed any memory effects from melatonin. My back seems to remember that I'm sleeping on a crummy mattress though.

Stephen

[zoolander]

Perhaps we can rummage through the research to see if we can find any human studies showing effects of melatonin on memory

[tintinet]

Variable effects, depending upon timing, dosages, etc., I think:

To wit:

1: Eksp Klin Farmakol. 2006 Jan-Feb;69(1):21-3.Links
[Effect of melatonin on memory, individual time perception, and anxiety in young people of different chronotype groups]
[Article in Russian]

Arushanian EB, Baĭda OA, Mastiagin SS.

Chronic administration of the pineal hormone melatonin in a low dose (0.75 mg) improved memory and optimized individual time perception in a group of young volunteers. These changes were pronounced even two weeks after termination of the drug administration. The expression of the melatonin effect was depended on the chronotype of humans tested.

PMID: 16579054 [PubMed - indexed for MEDLINE]

[zoolander]

well well.

[stephen_b]

It seems that melatonin helps consolidate daytime memories (PMID 17910601) but, while it's actually peaking in the blood, worsens memory retention (PMID 18006748).

The author of the sleeping pill study was described as saying that melatonin's memory effects may be "hurting you" at night. He sees the antioxidant effects of melatonin good but the memory effects bad. I'm not at all a biochemist, but maybe memory consolidation requires temporary impairment of the ability to form memories. And if you are asleep anyway, I don't agree with the author of that paper that there is actually a problem ...

Stephen

[browser]

Why are we concerned about zebrafish and operant conditioning? Do zebrafish dream? Are we nothing but a collection of habits? I don't see how this study is at all applicable to humans.

[stephen_b]

The question is whether melatonin weakens the ability to form memories while it is at a higher level in the blood stream. The author of the study I cited found that it did in zebrafish, and he sees this as a harmful effect that comes with the good effect from melatonin also being an antioxidant. This is from the physorg article I linked in the first post. I am not inclined to agree with him that any temporary decline in the ability to form new memories is a problem, because I am usually asleep then and not taking in new memories. The PMID 17910601 article supports the idea that melatonin at night helps consolidate memories from the day, and I speculate that maybe suppression of the ability to form memories at night aids consolidation of daytime experience.

I seem to be doing a great job of sowing confusion tonight. Maybe I should quit while I'm, um, somewhere.

Stephen

[browser]

I seem to be doing a great job of sowing confusion tonight. Maybe I should quit while I'm, um, somewhere.

Stephen

You are not sowing confusion. I just don't think that a single study dealing with fish tells the story for humans. We've cured baldness and cancers in mice and rats. But humans are not mice or rats. Somewhat close, but as the resveratrol delivery debate goes on, for example, we see glaring differences between them and us.

[stephen_b]

The confusion was that everyone thinks I agree with the article about the study, whereas I disagree with it, so I stand by my statement that I'm sowing confusion.

Stephen

[browser]

The confusion was that everyone thinks I agree with the article about the study, whereas I disagree with it, so I stand by my statement that I'm sowing confusion.

Stephen

Many apologies.

[hamishm00]

why do we really care about reduced memory formation at night (when we're asleep)? Surely this is not important?

[quarter]

why do we really care about reduced memory formation at night (when we're asleep)? Surely this is not important?

In my younger university days I often woke up without any memory of the previous night and found it quite concerning, nothing to do with melatonin though.

[stephen_b]

why do we really care about reduced memory formation at night (when we're asleep)? Surely this is not important?

My point exactly. It may even be necessary to consolidate memories from daylight hour experiences.

Stephen