Sleeping

Q: Is there any specified time as to how long Qaylulah should be?

Q: Is it sunnah to renew the wudhu before sleeping or will the wudhu made previously suffice?

Q: For men and women, what is the appropriate and sunnah clothes to wear when one sleeps? Should the satr be covered when sleeping or can a man sleep with a t-shirt and shorts for example?

Q: Is it permissible to use or nap on silk pillow covers or silk bed sheets for men? What if it was given to me to use for medical purposes? (For which I obviously hold intentions upon).

Q: Please clarify the procedure regarding the hadith below.

1. Should one read the surahs once, then blow, then once again and blow, then again and blow. Or should one read 3 times then blow once? Or should one read once and blow 3 times?

2. Should one blow such that a bit of saliva comes on to one's hand when blowing?

It is narrated from Sayyidah ‘Aaishah (radhiyallahu ‘anha) that every night, when Nabi (sallallahu ‘alayhi wa sallam) went to bed, he would cup his hands together and blow over them after reciting Surah al-Ikhlaas, Surah al-Falaq, and Surah al-Naas. He would then rub his hands over whatever parts of his body he was able to, starting with his head, his face, and the front of his body. He would do so three times. (Sahih al-Bukhari, 5017)

Q: At what age should a child stop sleeping with her father in his room? 

Q: Can I sleep naked in my bed?

Q: Can a male sleep with another male in the same bed, with only their satar covered?

Q: Can you sleep at the of asr?

Q: We hear from scientists and doctors nowadays that adults need 6-9 hrs of sleep and teenagers need at least 9 and so on respectively. We also heard about great Ulama and still in the present time who only sleep a couple of hours.

My question is that does Islam have a stance on sleep and do you think we should follow this research?