A recent research by scientists from the University of California found that the lack of a good night's sleep had an adverse effect on romantic relationships, especially in expressing gratitude or appreciation of the other.
When sleep is less, even saying a simple 'thank you' may be difficult and this may leave the partner feeling unappreciated. Further, lack of sleep makes the other person indifferent to what the other is feeling.
"Poor sleep may make us more selfish as we prioritize our own needs over our partner's. You may have slept like a baby, but if your partner didn't, you'll probably both end up grouchy," Amie Gordon, a University of California Berkeley psychologist and the lead investigator of the study.
"Make sure to say 'thanks' when your partner does something nice, let them know you appreciate them," researchers advised.