The Queen spent a night in the hospital for some 'preliminary investigations' after canceling a trip

• The Queen spent Wednesday night at the hospital for preliminary medical checks, according to the BBC.
• The 95-year-old monarch returned to Windsor Castle on Thursday afternoon and is "in good spirits."

Queen Elizabeth II is back at Windsor Castle after spending Wednesday night in the hospital for "preliminary medical checks," BBC News reported.

Earlier this week, the 95-year-old monarch canceled a trip to Northern Ireland at the last minute on the advice of her medical doctors.

Buckingham Palace told the BBC that the Queen returned to Windsor Castle around lunchtime on Thursday and is "in good spirits," despite being disappointed about her canceled visit to Northern Ireland.

Her hospital admittance is not related to COVID-19, the outlet reported. Doctors reportedly advised her to rest for a couple of days following multiple public engagements.

Buckingham Palace did not immediately respond to Insider's request for comment.