Can I recite the Shahada before going to bed?

Dear questioner,
Thank you for your important question.
May Allah, Most High, reward you for your desire to increase in knowledge.

This practice is valid. When a Muslim recites the testimony of faith (shahada), it is an act of worship. It is not just recited due to fear of polytheism. A ruling of polytheism is only applied upon an action done with the knowledge of it being a polytheistic action.

Reciting the testimony of faith (shahada) is a righteous form of remembrance. The scholars mention that its repetition has many virtues. Among them are;

A pure admittance and emphasis of the Shahada.
A renewal of belief and certainty
A removal of ignorance
(Ibn Allan, Futuhaat ar-Rabbaniya)
The Shahada may be recited at any time.
And Allah alone knows best,
[Ustadh] Omar Popal
Checked and Approved by Shaykh Faraz Rabbani