What is the ruling on supplicating to Allah while lying down in bed, given that one feels more humility and seclusion from people's eyes in this posture?

There is no objection to supplicating while lying on one's side or reclining if it is accompanied by devotion and a present heart. This is supported by several pieces of evidence:

1. The Almighty Allah's saying: (And when adversity touches man, he invokes Us, lying on his side or sitting or standing) Yunus/12. This indicates the permissibility of supplicating in all states.

2. The Almighty Allah's saying: (Those who remember Allah while standing or sitting or [lying] on their sides) Al Imran/191. This verse is used to infer that remembrance includes all postures.

3. The action of the Prophet, peace be upon him, as it is authentically reported that he supplicated while lying on his side.

4. Reports from the Pious Predecessors that indicate its permissibility.

5. Devotion and a present heart in supplication are more important than adhering to a specific posture.

Nevertheless, one should not exclusively designate this posture for supplication or intentionally always use it, as among the recommended manners of supplication are facing the Qiblah and raising the hands.