1. He called me while I was in bed.

2. he called me while I was sleeping.
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Does #1 mean #2? What is the meaning of 'in bed'?

3 answers

1. He called me while I was in bed.
2. he called me while I was sleeping.
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Does #1 mean #2? What is the meaning of 'in bed'?

3. in bed: beneath the covers of a bed
(This is the definition of 'in bed.')
What is 'bed cover'? Is 'bed cover' different from 'blanket'? Do people sleep with bed covers or with blankets?
Being "in bed" and "sleeping" are not necessarily the same. One may sleep in a hammock, on a sofa, outdoors in the grass, in a chair, any number of places. And people do things in bed that are not sleeping, from reading to watching TV to sex, etc.

Bed covers refer to sheets and blankets, bedspreads, coverlets, etc. The things that cover the mattress.
In other words, to be IN bed is to be atop the mattress, covered with the bed covers, be it a sheet, a blanket, a coverlet, or a combination of them.