Question about rest periods

So we all know that you're not allowed to strategize and talk about the game during the rest period. But what if you happen to think of a potential strategy or move while you're at the hotel? Are you allowed to write it down or set a reminder on your phone for the next morning, or do you have to hope you remember it the next day? Or, alternatively are you just so tired your only thoughts are to eat food and go to bed?