It does seem that some people do not wake up in a good mood and it will take them several cups of coffee before they can function properly.I am a morning person, it's my favourite part of the day so I am likely to be in a good mood unless I am ill or I have not slept well. We all have different body clocks so feel more alert at different parts of the day. Grouchiness is associated with the sleep inertia phase, a period of time lasting from 5-20 minutes or maybe longer in which it takes a person to wake up properly. Research shows that it can be associated with tiredness but also having a bad attitude towards the day. If grouchiness only occurs during a working week and not at the weekend or days when you don't work it could mean you are grouchy at the thought of having to face your working day.