The typical male testosterone level is between 250ng/dl to 850ng/dl but it varies with age. Although it’s normal for testosterone levels to drop as men age, low testosterone can cause loss of libido, erectile dysfunction, mood problems, fatigue, and sleep disturbances.
Apart from that, it can be due to medical conditions like diabetes, high blood pressure, heart or thyroid conditions, poor circulation, low testosterone, depression, spinal and neurologic causes.
I suggest you to get an evaluation done from a urologist and get it evaluated.
I hope it helps. Take care and regards.