In scientific jargon it’s called nocturnal penile tumescence, but it’s more popularly known as “morning wood.” It’s the spontaneous erection that happens during sleeping or upon waking, both in adults and in babies. It isn’t connected to sexual stimulation but, as it seems, is associated with the REM phase of sleep.
All men, or at least nearly all men, who don’t suffer from erectile dysfunction experience nocturnal penile tumescence between 3 to 5 times during the nite. And yet, as discovered by the experts from the International Society for Sexual Medicine (ISSM), “the lack of a morning erection isn’t necessarily a cause for alarm, as it can also occur the a man wakes up during a non-REM sleep cycle and in such case there is no spontaneous erection.
Apart from that, it remains true that the presence (or absence) of a morning erection can provide information on one’s sexual health, and in particular regarding erectile dysfunction which is often connected to both physical and psychological factors. If a man is suspected of suffering from erectile dysfunction, yet he still experiences morning erections, it is more probable that the condition has psychological origins as this shows that the system required for an erection are in working order. And vice versa, in the absence of nocturnal penile tumescence, the origins of the disorder are more likely to be physical in nature.HFTHQ 20-28