Thanks for updating your query here.
Normal erections (initiating and maintaining) during the night and in routine life rules out erectile dysfunction in your case. The problem with your sexual desire lies in the levels of hormone testosterone. It is usually produced by testes and is important in maintaining masculine characteristics, urge for sex and erection. There are a number of possibilities for reduced testosterone levels in the body.
1)Congenital- that is by birth
2)Primary hypogonadism where is there is testicular dysfunction
3)Secondary hypogonadism- where there is a dysfunction in hypothalamus tract which regulates hormonal secretion
4)Injury to testis
5)Androgen Receptor deficiency
6)As a normal part of ageing
Apart from the above reasons, a psychological factor plays a crucial role in the sexual function in man.
I would like to suggest you to avoid all the stress and meditate for atleast 30 minutes a day for a healthy mind. Also I advise you to consult a physician for a complete workup on your hormonal status for further management.
Hope this helps.