I work shifts, and that isn't good for my already unusual sleep rhythm. To battle the sleeplessness and following zombie state every time my schedule changes, I got some melatonin pills. Melatonin is a hormone that is produced naturally in the body when it is dark. It is a part of the system that signals the body when it is time to fall asleep.
It does, usually, make me fall asleep faster. It also makes me wake up earlier, which is a good thing when the alarm rings at 6 AM. After taking a melatonin pill before midnight, it feels like I have had a fuller night of sleep early in the morning. It is easier to drag myself out of bed.
What I didn't expect was the effect the drug had on my experience of time. I don't just wake up as easily after 6 hours with melatonin as after 9 hours without, it also feels like it has literally been 9 hours since I fell asleep. I have often woken up at 3 or 4 and thought I have overslept, because my sense of time has been wrong. I have woken up half an hour before my alarm in a panic, because I have been certain that I overslept!
We all wake up several times every night. Many people can't remember this. I usually do. When I take melatonin, I notice the awakenings even more, because there is usually some anxiety involved. It is harder to fall back asleep when my stomach is a tight knot and my mouth is dried out. Sometimes, I am sure that I have been lying still in bed, trying to sleep, for more than an hour. Then I look at the time. It has only been 20 minutes.
The altered sense of time lasts into the morning sometimes. It can feel like I have spent half an hour in the bathroom, and that I have certainly missed my bus, when it has only been 10 minutes. This is really fun when work is slow.
I have asked other people on IRC and on LD4all for their experiences, and nobody else has experienced this side effect. It isn't stopping me from using the pills now and then. I'd rather have a moment of panic in the morning than a full shift as a zombie.