Bette Midler, 78, says the key to her nearly 40-year marriage is sleeping in separate bedrooms

• Bette Midler, 78, says sleeping in separate bedrooms is the secret to her long-lasting marriage.
• She told Entertainment Tonight that they have slept separately since the start of their relationship.
• Midler isn't the only celebrity who has been open about "sleep divorce."

Bette Midler, 78, says the secret to her long-lasting marriage is not sharing the same bedroom.