I know that in the morning, a person should ritually wash his hands – Netillat Yadayim – and say the prayer Modeh Ani. Are these necessary after a nap? Does the length of the nap make any difference?
AskTheRabbi.org answered:
Modeh Ani and washing Netillat Yadayim with a blessing are only for when a person wakes up in the morning. Otherwise if a person sleeps for more than thirty minutes at another time of the day he should wash his hands without reciting a blessing.