tl;dr They don't know for sure. It might be because your brain is getting older, days are less structured, depression, loneliness, grief over the loss of a lo

tl;dr They don't know for sure. It might be because your brain is getting older, days are less structured, depression, loneliness, grief over the loss of a loved one, menopause, weight gain, and medication. Recommendations for better sleep are the same as for the general population.