I’ve seen this mentioned in several different places but other sources have no mention of it.
It sounds to me like sexist nonsense but then she’s only human and maybe something did happen to her during the mission?
I had never heard that but I have heard a female “lost cosmonaut” recording where she breaks down during re-entry when the heat shield fails. However the lost cosmonauts are considered a fabrication so take that as you will.
Ah, hell, GQ. Never mind 
This astronautix article goes into detail, though is really poor on sourcing its statements. I guess you could look at the diaries/memoirs of the Soviet space officials mentioned in the article: Vasili Mishin, Nikolai Kamanin, and Sergei Korolev.
During the period of reentry when the heat shield is most stressed, the vehicle is surrounded by a plasma sheath (air heated to dissociation) which is impossible to transmit through. Also, on a base-end type shield, the most likely type of failure is thermal fracture, resulting in a progressive crack(s) in the shield and loss of structural integrity. If the damage becomes large enough to disrupt the standoff wave or chunks of the shield come loose, the resulting instability will cause the capsule to tumble violently and probably break up in short order.
Stranger
No reference to her freaking out in the Wiki article, and apparently she’s still quite popular in Russia: Valentina Tereshkova - Wikipedia
Here’s the Perfect Master on the “lost cosmonaut” myth: Are there really “lost cosmonauts” stranded in space? - The Straight Dope
Thanks for the answers everyone!
I have been trying to find a copy of a mid-1960’s book “Soviet Space Hoax”-it was a book written by an ex-Russian space engineer, published in the West. I do remember that the author said that Valentina suffered from motion sickness, and landed with her nerves shot.
I’ve heard the claim that Tereshkova freaked out or lost emotional control on her flight, and thus never flew again and supposedly set back the chances of other female 'nauts. I know I read it two or three places, but as others have pointed out, the current histories make no mention of it. I strongly suspect a US-side rumor, maybe even a very casual one, to discredit both the Soviet program and those uppity wimmen…
I bet the chimps shit their diapers on reentry too. 
Geez, who wouldn’t? I’d be screaming the whole way down. The poor woman wasn’t even a pilot. All the early US astronauts were jet pilots and several had been test pilots.
That would have to be the first time anyone wanted to get the hell out and hit the chute rather than fly it down. 
If she did lose it in flight (which inclined to believe is nonsense), it certainly didn’t affect her post-space career. The woman definitely made the most of it. The wiki article is impressive for any man. But for a woman? In Russia? In the 70’s & 80’s? Holy cow. I’d like to meet her just to shake her hand.
The greatest nation in history (America) ran its space program in the open with televised flights, interviews. The Evil Empire, the Kremlin slavemasters who murdered millions or people and oppressed hundreds of millions, ran its program shrouded in secrecy. If there were false rumours about Tereshkovska’s performance, then the reason is obviously that is what happens when you cover things up and hide in darkness. Not any disinformation program.
Okay, yeah, well, I think you missed my point.
I doubt she had a nervous breakdown, but there was some general rumbling that her time in orbit could have been better used by a fully trained astronaut. Terehkova was really just a paratrooper given a crash course in being an astronaut. While in orbit she was not able to do as much as a fully trained astronaut would have done. While her flight did give prestige to the Soviet Union, it was an example of how they were using the space program for stunts rather than research into the next step. Meanwhile, the USA was using its flights to advance the space program.
I suspect this story is just sour grapes mixed in with a little bit of good ol’ chauvanism.
This is relevant by the thinnest and flimsiest of threads:
Israeli Minister of Defense Yitzchak Rabin had a nervous breakdown during the Six Day War in 1967.
I will now pipe the fuck down and stop distracting everybody.
In 1967:dubious:
Hardly any launches, US or Soviet, had gone beyond ‘spam in a can’ by the time of Tereshkova’s flight. There was only so much we could learn from seeing how well 'nauts could flip switches in weightlessness. While it seems silly today, sending a woman up to check flight physiology was a reasonable and worthwhile step, and didn’t need a Harrison Schmidt or even a John Glenn caliber candidate.
I disagree, a month before Tereschkova’s flight Scott Carpenter was so busy in his capsule he overshot his drop point. His mission was full of science projects and photography work.
Just three month’s later Schirra was running engineering tests that were critical for development of the future orbiters (Gemini, i.e.). Calling these missions "Spam in a can’ is unfair IMHO.
Tereschkova, by comparison, took some photos and didn’t do much else despite having much more time in orbit.
Having some physioloigy data was all well and good, but it did not advance the Soviet program they way it needed to advance.
Wasn’t Carpenter in disgrace for screwing around, more or less sight seeing rather than performing his tasks?
TheWikipedia articleis very favorable of him, but he never flew again.