The finding supports several previous studies showing that men who are under stress produce less testosterone, which has an effect on their libido.
The authors suggested couples should be made aware of these risks and attempt timed sessions for no longer than three months at a time, with breaks for a few months in between.
"Timed intercourse seems to impose a substantial degree of stress on male partners, inducing erectile dysfunction and, in some cases, causing them to seek extramarital sex," they wrote in the Journal Of Andrology.
"It is clear that the greater instances of timed intercourse trials, the more incidences of erectile dysfunction and extramarital sex and the greater the desire to avoid sex with the intended partner."
The authors said that having to sleep with their partner at a specific time "becomes a burden and is carried out as a job to be done, which imposes further stress". They believe higher levels of cortisol, the stress hormone, being produced by the body was to blame for lower testosterone.
- DAILY MAIL