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If one washed his hands at night must he rewash in the morning:
A. One did not go back to sleep after the initial washing:
If one woke up prior to dawn and washed his hands, he does not need to rewash his hands in the morning if he did not return to sleep before dawn.
B. One went back to sleep after the initial washing:
If one returned to sleep prior to dawn, then he must rewash his hands three times inconsecutively upon awakening. Nevertheless he does not recite a second blessing upon rewashing if he already recited the blessing upon washing the first time. [Regarding if one may delay the blessing until after washing upon awakening the second time-see the previous Halacha.]
If one awoke in middle of the night and washed hands, then if he did not go back to sleep before Alos he is not required to rewash his hands in the morning. If he did return to sleep then he is to rewash his hands properly in the morning. A blessing is not recited after the second washing unless he did not recite a blessing after washing the first time.
 Based on Siddur which rules that if one did not sleep at night the spirit of impurity certainly does not reside on the hands and one is thus not required to wash his hands in the morning. [See Halacha 16B]
Other Poskim who rule like Siddur: Rav Chaim Hakohen, student of Rav Chaim Vital, states that the impure spirit does not reside unless one sleeps at night. Thus if he woke up and washed his hands before Alos he does not need to rewash after Alos. So rules also Derech Chaim; Ramaz; Birkeiy Yosef 4/5; Mikdash Melech Vayishlach; Soles Belula 4/10; Divrei Shalom Shieila 48 in name of Arizal. [Kaf Hachaim 4/47]
Ruling of Admur in Shulchan Aruch: In Kama 4/14 [based on Rama 4/14] Admur rules: “If one woke up prior to dawn and washed his hands, it is proper (lit. Tov) for him to rewash his hands three times inconsecutively after dawn [even if he had not gone back to sleep in the interim], as possibly the night causes the impurity to reside on ones hands independent of sleep.” To note however that even according to the Kama it is only proper to wash and it is not an obligation. This differs from the wording in the Rama 4/14 which simply writes one is to wash without a blessing. Vetzaruch Iyun why according to Admur in Kama this is not an obligation due to the doubt.]
Other Opinions: Rama 4/14 rules one is to wash without a blessing. According to all there is no need to refrain from learning Torah prior to washing after Alos. Likewise one may be lenient to consider Alos as 72 minutes. [See Piskeiy Teshuvos 4/17 footnote 159] Biur Halacha 413 “Kol Halayla” rules that if one woke up in the beginning of the night and washed with a blessing then before Davening he is to go to the bathroom and wash hands again and recite another blessing. So also rules Shulchan Hatahor 4 footnote 1 and that so was custom of Chozeh Melublin; Birchas Habayis 32/11. If however he woke up close to Alos then a second blessing is never recited even if he went back to sleep. [M”B 4/32]
 Siddur; Kama 4/14
 This refers to a sleep of 60 breaths and applies even if one only slept a temporary sleep. [See next footnote]
 As in a case that one returned to sleep a set sleep before Alos the spirit of impurity definitely resides on one’s hands and the hands must thus be washed properly. [Siddur; Kama ibid] Furthermore even if one returned to sleep a temporary sleep [nap] of 60 breaths it is possible that the spirit of impurity resides as explained in Chapter 3 Halacha 6.
 The reason a blessing is not repeated: The Sages instituted washing with a blessing only one time after one awakens and becomes a new creation. [See Halacha 2] This follows the same rule as all morning blessings. [Siddur; Kama 4/14; Hence once the blessing has been said one has fulfilled his Rabbinical obligation and another blessing may not be recited.] In Kama 4/14 Admur adds: “and upon awakening a second time one does not become a new creation, as one only becomes a new creation once and not twice.” The Ketzos Hashulchan 2/6 connects this addition of the Kama into the ruling of the Siddur.
Other Opinions: Biur Halacha 413 “Kol Halayla” rules that if one woke up in the beginning of the night and washed with a blessing then before Davening he is to go to the bathroom and wash hands again and recite another blessing. So also rules Shulchan Hatahor 4 footnote 1 and that so was custom of Chozeh Melublin; Birchas Habayis 32/11; If however he woke up close to Alos then a second blessing is never recited even if he went back to sleep. [M”B 4/32]