She's right, establish a pattern and you'll be fine (generally). I say generally as there is an optimal time to sleep that'll leave you better rested. I tend to sleep a regular 1-6 hours between 6am and 12 midday and though it keeps me going I still feel a bit tired. Doctor explained it was because of the time I was sleeping, not the best hours and warned me it could lead to several health problems in the long term. Whoops.