Incorrect: "I laid in bed last night, unable to sleep." (Lie vs. Lay)

Incorrect: "I laid in bed last night, unable to sleep."
Correct: "I lay in bed last night, unable to sleep."

Lie, lay, laying, lying, lain, laid--Aaack! This one haunts me. If I have trouble with it, I can imagine many of you do, too. Even if you memorize the difference in meanings, you may not be able to remember the conjugations for each tense. Don't worry about it. Come back to this blog any time you need to double-check.

"Lie" means "to recline." 

Present Tense: lie or lying, as in "He always lies down for a nap in the afternoon."
Past Tense: lay, as in "He lay down yesterday at 10:30 a.m."
Past Participle: lain, as in "The sword has lain there for many years."

"Lay" means "to set something down."

(You must to include the "something," A.K.A. the object of the verb.)

Present Tense: lay or laying, as in "The hen is laying eggs."
Past Tense: laid, as in "I laid my pen there this morning."
Past Participle: laid, as in "I have laid out all the paperwork."

BONUS ROUND:

Question: If lie means to recline, shouldn't that traditional prayer say, "Now I lie me down to sleep," rather than "Now I lay me down to sleep"?

Answer: No, "Now I lay me down to sleep" is correct, because the speaker is saying that he or she is setting themselves down to sleep. The direct object "me" clarifies that "lay me" is being used to mean "set myself down." If you removed the "me," you would need to say "lie" rather than "lay," as in "Now I lie down to sleep."