# Shedding light on night‐time erections: Determining the feasibility of nocturnal erection detection with penile transdermal light reflection of haemoglobin

## TL;DR

This study explores using light reflection and temperature to detect night-time erections, aiming to develop a non-invasive diagnostic tool for erectile dysfunction.

## Contribution

The study introduces a novel method for nocturnal erection detection using transdermal light reflection of haemoglobin and penile temperature.

## Key findings

- LRH values and penile temperature significantly increase during nocturnal erections (p < 0.01).
- Visual detectability of erections was feasible for 80% with LRH and 90% with temperature data.
- The largest temperature increase was observed in the last erection, reaching 1.29°C after correction.

## Abstract

Utilizing penile saturation and temperature measurements presents a promising avenue for the development of an innovative sensor system aimed at nocturnal erection detection. This study aims to determine the feasibility of erection detection with light reflection of haemoglobin (LRH), as a precursor for penile saturation measurements, as well as penile temperature by comparison with simultaneous overnight RigiScan measurements.

This is a proof‐of‐concept observational study on 10 healthy volunteers with a cross sectional design. A penile transdermal haemoglobin and temperature sensor was developed to measure penile LRH through real‐time monitoring with receiving photodiodes and emitting light‐emitting diode (LED). Besides statistical analysis on LRH, temperature and RigiScan data, a visual assessment was done to determine detectability of changes in the LRH and temperature course during the RigiScan‐annotated erections.

A total of 40 nocturnal erections from 10 healthy volunteers were annotated with the RigiScan. The LRH values significantly increase during a nocturnal erection (p < 0.01) and penile temperature (p < 0.01). The largest elevation of temperature was seen in the last erection, with an increase of 0.94°C. The corrected temperature shows an increase of 1.29°C in the last erection. Furthermore, visual detectability was feasible for 80% of the erections with LRH values and 90% with the temperature output.

Penile LRH and temperature have the potential to serve as an alternative methodology for nocturnal erection detection compared with the currently applied circumference and rigidity measurements. This is an important step in the development of a patient‐friendly and modernized tool for erectile dysfunction diagnostics. An improved sensor should be developed to allow for calculation of saturation percentage from LRH values. In combination with penile temperature measurements, this allows for conduction of further validity studies to work towards translation into clinical practice for non‐invasive ED diagnostics.