# Erection? **URL:** https://boards.straightdope.com/t/erection/301823 **Category:** Factual Questions **Created:** [April 30, 2005, 3:22am UTC](https://boards.straightdope.com/t/erection/301823 "2005-04-30T03:22:14Z") **Posts on this page:** 4 **Page:** 1
### Author: ![shaylaomega](https://avatars.discourse-cdn.com/v4/letter/s/3d9bf3/32.png) [@shaylaomega](https://boards.straightdope.com/u/shaylaomega) #### Post date: [April 30, 2005, 3:22am UTC](https://boards.straightdope.com/t/erection/301823/1 "2005-04-30T03:22:14Z")
Why is it that men nearly always wake up with an erection? It’s always puzzled me… ---
### Author: ![BobT](https://avatars.discourse-cdn.com/v4/letter/b/8e8cbc/32.png) [@BobT](https://boards.straightdope.com/u/BobT) #### Post date: [April 30, 2005, 3:27am UTC](https://boards.straightdope.com/t/erection/301823/2 "2005-04-30T03:27:40Z")
Read about REM sleep. It’s pretty much guaranteed when you’re in that state. It’s also one thing doctors will ask about if you think you’re not able to pull off the feat anymore. If you can do it asleep, then the problem is more likely in your head than your … ---
### Author: ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri) #### Post date: [April 30, 2005, 3:30am UTC](https://boards.straightdope.com/t/erection/301823/3 "2005-04-30T03:30:39Z")
It means he has been dreaming shortly before waking up. Men invariably have penile erections (and women have clitoral erections) during REM (dreaming) sleep. This is most likely due to the fact that muscle tone is lost during REM sleep, presumably to keep you from acting out your dreams. Loss of tone in the muscles associated with the penis allows blood to flow in and produce an erection. ---
### Author: ![voltaire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voltaire/32/313_2.png) [@voltaire](https://boards.straightdope.com/u/voltaire) #### Post date: [April 30, 2005, 3:30am UTC](https://boards.straightdope.com/t/erection/301823/4 "2005-04-30T03:30:40Z")
[Guys: Why do men get so many erections while asleep? (could be TMI)](http://boards.straightdope.com/sdmb/showthread.php?t=272350) [Morning erections](http://boards.straightdope.com/sdmb/showthread.php?t=117611) [what’s the deal with morning wood?](http://boards.straightdope.com/sdmb/showthread.php?t=192011) [Morning woody after a dream](http://boards.straightdope.com/sdmb/showthread.php?t=11160)