The Hid"a (Rav Haim Yosef David Azulai, 1724-1806), in his work Abodat Ha’kodesh (listen to audio recording for precise citation), writes that one must make a special effort on Shabuot morning, after staying awake through the night, to pray properly. Many people tend to doze during the prayer service on Shabuot morning, such that they do not recite the words properly, skip sections of the service, and certainly do not concentrate on the meaning of the words. The Hid"a writes that "Yasa Secharam Be’hefsedam" – these people lose their reward for learning throughout the night by failing to pray properly in the morning. After staying awake studying Torah throughout the night, one must make an effort to remain fully awake and alert during the prayer service on Shabuot morning so he can pray properly.
It should be noted that the Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909) viewed the period of Sefirat Ha’omer as an extended Tikkun ("repair" of spiritual imperfections in the upper worlds) that begins on the second night of Pesah and reaches its culmination in the Musaf prayer on the first day of Shabuot. Accordingly, the Shaharit and Musaf prayers on Shabuot morning are laden with spiritual significance, and it is critical for one to recite these prayers properly. One who sleeps through these prayers, or does not recite them as he should, runs the risk of forfeiting the spiritual achievements of the entire Omer period. Therefore, it is critical after staying awake on Shabuot morning to muster all one’s strength to pray properly on Shabuot morning.
One who suspects that he will be unable to remain awake and alert through the end of the Musaf prayer should recite Shema and then take a nap. It is preferable to complete the prayer service later, after sleeping and rejuvenating oneself, than to risk dozing during the Tefila.
When is the earliest time for reciting Shaharit on Shabuot morning?
Generally speaking, one should not recite the Amida prayer of Shaharit before sunrise (Netz Ha’hama). On Shabuot morning, however, some authorities permit congregations to begin the Amida before sunrise. Since it is very difficult for people to pray properly after remaining awake throughout the night, there were some who held that the prayer may be recited earlier to help ensure that everyone will be able to properly pray the entire service. This is the ruling of the Peri Megadim (492) and the Mishna Berura (89:1, and in Sha’ar Ha’siyun 5). There are many congregations that nevertheless ensure to wait until sunrise before beginning the Amida on Shabuot morning, and though this is certainly an admirable custom, those who pray the Amida before sunrise certainly have authorities on whom to rely. Indeed, the practice of Hacham Baruch Ben Haim was to pray the Amida before sunrise on Shabuot morning, and, as mentioned, this practice is perfectly acceptable. This is the ruling of Rabbi Karp in his work Hilchot Hag Be’hag (p. 132; listen to audio recording for precise citation).
It should be noted that congregations that recite the Amida before sunrise on Shabuot morning must ensure not to recite Shema before the earliest time for Shema, which occurs approximately 10-15 minutes after dawn. (Generally, however, by the time these congregations reach the Shema prayer, that time has already passed.)
Summary: One must make a special effort to remain awake and alert throughout the prayer service on Shabuot morning after remaining awake through the night. If one suspects that he will be unable to remain awake and pray properly throughout the service, it is preferable to recite Shema, take a nap, and then complete the prayer service properly. Although the Amida of Shaharit generally should not be recited before sunrise, some congregations have the custom of reciting the Amida on Shabuot morning before sunrise in consideration of the difficulty entailed in remaining awake and alert throughout the prayer service. This is certainly an acceptable practice.
