Asked by: BBC Focus Magazine
Being excited makes you think about the next day and imagine different scenarios. That requires some concentration, which keeps you awake.
As you lie there, tired but not sleepy, you may start to imagine how exhausted you’ll feel the next day if you don’t get enough sleep. So now you’re thinking about your own insomnia, and the more you focus on it, the more your mind races and the less sleepy you feel. Stress, worry and excitement also cause your body to produce adrenaline and cortisol, which raise your heartbeat and make you even more wide awake.