Of course, this sounds like an absurd reason, especially during summers when you'd want to take a shower before bedtime. But it is suggested to not take a bath before sleeping because your body temperature drops before bedtime. And since you take a bath, the hot water will only spike your body temperature and then it takes longer for your body to cool down. Hence, if you wish to fall asleep like a baby, avoid taking showers during bedtime.
by Dhwani Vora