Another common thing that people do in their lifestyles is drink coffee or tea or soda. All of these things contain caffeine and caffeine is a very common drug and it keeps us alert and awake. The trouble with it is it lasts for a really long time. It has a very long half life - how long it takes to get rid of half of it. And so as we grow older, we may detoxify any drug (including caffeine) less well. So what happens is, we may drink a cup of coffee (two, maybe three, maybe four) in the morning and think that we're fine. But what happens is seven hours after you've taken those four cups of coffee by 8:00 AM, it's three o'clock in the afternoon. You still have two cups of coffee in you. Seven hours after that (the half life of caffeine) it's 10 o'clock at night and you still have a full cup of coffee in you. Caffeine takes a long time to clear through the liver system - again, it's half life is long. So even though people may say "but Dr. Sahni, I have been having a pot of coffee since I was 20 - how could that possibly be giving me insomnia now?" It may be that they're 70 and their liver is 50 years older and it just simply doesn't detoxify as well. After all, again, caffeine is a long acting stimulant and irritant and it may absolutely affect our sleep. Sometimes not falling asleep but staying asleep - because again, at the beginning of the night, sleepiness is high and you've been up all day. Sleepiness is high, noise is low. Noise literally could be a dog barking outside. It could be caffeine buzzing, it could be anxiety, it could be pain in your hip. But as the night goes on, you've gotten a little bit of sleep - you're less tired - and the noise that you ignored before (because you were so tired that you slept through the dog barking) begins to bother you. And so even though caffeine may not stop you from falling asleep, it may stop you from staying asleep. Now we already know everybody wakes up during the night, but with more caffeine on board, we may be more aware of it and we may stay awake for longer. So again, rules of thumb for caffeine would be simply: less is more and earlier is better. We have to find the place that works for us. It's rare that somebody has to have a zero tolerance policy to caffeine, but if you're having trouble sleeping, that's certainly one thing to look at and to gradually withdraw. If you've ever gone cold turkey on caffeine, you know it's terrible. There is a very big withdrawal, it could precipitate a headache or even a migraine in people who are prone, but it also can just make us feel sick or constipated and very fatigued. The withdrawal is the opposite effect of the drug itself.