The fruit (Banana) takes some time to digest and sleeping immediately after eating this fruit can cause digestional problems. banana is a fruit that spikes the hastamine level in the body, and if the level of hastamine is high it is known to cause mucus buildup Which is a major problem to avoid if you're dealing with cold or catarrh especially at night.
This problem can also lead to a disturbing sleepless night because the body would be forced to get rid of the mucus.

ASTHMATIC PATIENTS
People suffering from Asthma is advised not to take banana at night because of the problem of mucus which can make breathing difficult.
If you want a good night sleep then i would advice you take something else in place of banana.