Caffeine is a mild diuretic. So if you are drinking lot of coffee and tea you might be slightly dehydrated. If you are not balancing your caffeine intake by replacing it with water. One of the problems with caffeine is that we usually take it in adding other ingredients to it like dairy and sugar. Sugar can also be a mild diuretic meaning that we are losing more water than we are taking in. So if we combine the sugar and the caffeine it has a stronger effect on our body. The other issue with caffeine is over time we develop a resistance to it meaning that we need more to get us through the day, more to get us to that level of alertness than we did in the beginning. Even though caffeine is only slightly dehydrating there are some other aspects of caffeine intake that you might wanna keep in mind. One it that it can make you anxious, it can make you jittery and it can make you lose sleep at night. So even though caffeine is only slightly dehydrating, you need to make sure that it is not affecting other aspects of your health like your sleep, like your anxiety levels. Be sure to balance it with enough water to make sure you are not dehydrated.