Yes, you may sleep in your husband's bed while niddah if he is out of the country.

The general rule is that while niddah you may lie in your husband's bed while not in his presence, and sit on his bed even if he is present. These halachot are stricter for the husband. He may not lie on his wife's bed while she is niddah, even while not in her presence, but may sit on her bed as long as she is not present.

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