Hi, Since you are getting good erection during sleep than your problem can be psychological not physical. Firstly, I would advise you for certain lifestyle modifications and non medicinal measures to get erection. Try to be more passionate towards your partner. Spend quality time together and spend more time in foreplay. Avoid smoking and drinking if you have a habit of it. Exercise regularly which will boost your testosterone level and subsequently you may get good erection. Make your bed room more comfortable and conducive for the sex by dim light or light music. If all these measures doesn t help than you can take Sildenafil or Tadanafil group of drugs under medical supervision for 3-5 days and once get your confidence again, you can discontinue these medicines. Hope this answers your question. Please feel free to ask for follow up question and I will gladly answer you. Best wishes, Dr B R Hudda