I am going to bed I am going to go to bed | i'm going to bed
Theydo.Thefirstsentencetellsmethatthispersonisgoingtobedimmediatelyorsoon.Thesecondsentencestellsmethatthispersonplanstogotobedinthefuture.Iamnotsurehowlongitwillbebeforeheorshegoestobed.Peoplesometimesgotobedforreasonsotherthansleep.Theymaygotheretorestandrecoverwhentheyaresick.Theymaygotheretomakelovewithsomebody.SomepeopleevenliketowatchTVorlistentomusicwhiletheyareinbed.Inyoursentences,Iwouldunderstandthespeakertomeanthatheorsheplanstosleep.Ifthatspeakerhadsomeotherideainmind,heorshewoul...
They do. The first sentence tells me that this person is going to bed immediately or soon. The second sentences tells me that this person plans to go to bed in the future. I am not sure how long it will be before he or she goes to bed.People sometimes go to bed for reasons other than sleep. They may go there to rest and recover when they are sick. They may go there to make love with somebody. Some people even like to watch TV or listen to music while they are in bed.
In your sentences, I would understand the speaker to mean that he or she plans to sleep. If that speaker had some other idea in mind, he or she would have to explain it.