Morning wood is an informal term referring to the phenomenon of nocturnal penile tumescence (erection) during and immediately following sleep.

Assessment by self-report, behavioral, and nocturnal penile tumescence measures before and after treatment with cognitive behavior therapy.

Erection during sleep or upon waking up are known as nocturnal penile tumescence (NPT).

Such an erection is medically known as nocturnal penile tumescence (informally: morning wood or morning glory).

Nocturnal penile tumescence testing (NPT) may be useful in distinguishing mental from physical impotence.

Erections during sleep or when waking up are medically known as nocturnal penile tumescence and colloquially referred to as morning wood.

Nocturnal penile tumescence (NPT) test.

Nocturnal penile tumescence (NPT): This test measures a man's erectile function while he is sleeping.

Regularly, men who experience erectile dysfunction are given a nocturnal penile tumescence (NPT) test, usually over a three-day period.

Morning wood is an informal term for a morning erection, for which the technical medical term is "nocturnal penile tumescence".

All men without physiological erectile dysfunction experience Nocturnal penile tumescence, usually three to five times during the night, typically during REM sleep.

Equally, a male erection can occur during sleep (nocturnal penile tumescence) without conscious sexual arousal or due to mechanical stimulation (e.g. rubbing against the bed sheet) alone.

Thase ME, Reynolds CF 3rd, Jennings JR, et al.: Nocturnal penile tumescence is diminished in depressed men.

Nocturnal penile tumescence (NPT) stamp test; Nighttime penile tape test A strip of four to six postage stamps (any kind) is used for each test.

The goal of nocturnal penile tumescence testing is to determine whether a man can experience an erection while sleeping after reporting he is unable to experience an erection while awake.

Further testing: Following completion of this phase, the doctor should be able to determine the general type of dysfunction and the need for additional testing such as penile or pelvic blood flow studies, nocturnal penile tumescence testing, penile biothesiometry (nerve testing), or additional blood tests.