Also, people can be exhausted for any number of reasons so trying to pin it on them fasting is not the answer. Ramadan is considered the holiest month of the year for Muslims and it's not just about the fasting, but the acts that come before and after. Things such as praying and reciting the Quran at night or during the day are quite common since it's a month of seeking forgiveness as well.
In some countries, some people decide to sleep only after morning prayers while others sleep several hours after eating giving their body time to digest their food and then get up 15 minutes before morning prayer to grab something to eat before it's too late (or just skip this altogether). It differs from individual to individual. I personally don't bother waking up to eat something since I eat a normal meal when I break my fast and that's good enough for me. Your body becomes extremely disciplined and most kids start fasting at the age of 10 or so. Now, of course, some people tend to overdo things in the sense that they have a feast when they break their fast, or they might push themselves to keep praying or reciting when they should clearly get sleep and pick things up the next day, but that's a personal choice. Fasting is about considering the plight of those less fortunate, about seeking forgiveness and getting closer to God.
Aside from this, I can't say much more. Everyone here knows how to use google to look at the benefits of fasting and make their own decisions after giving it serious thought (and hopefully actually trying it for several days). If you still disagree, well, that's your prerogative. Hopefully what I wrote was educational to someone on here.