I'm Alicia, thanks for your question. I'm happy to help you today.
Everyone has trouble falling asleep from time to time, so it's not so incredibly unusual if you have this problem every now and then. There are a lot of reasons why you might be having trouble getting to sleep on one particular day, even if you normally keep to the same sleep schedule on other days. You might have had an increased level of stress
on the day you had trouble falling asleep, you might have taken in too much of a stimulating substance (like caffeine or nicotine) too close to bedtime, you could have a lot on your mind (worries, etc) or it can also happen due to certain physical or mental disorders (like depression, anxiety
, certain physical illnesses - although in this case, you would probably experience more than just one day of trouble falling asleep). If you had too much mental stimulation too close to bedtime (watching a scary movie, reading a book that you were very involved in, etc) then that can also play a role.
You might find this information helpful:
If you continue to have trouble falling asleep, then I would suggest you discuss it with your doctor. But if it's just happened once or twice, then it's nothing to worry about. I hope that helps. Please let me know if you need additional assistance.