Some drugs and effects of alcohol can last well into the next day and although you think your thinking is clear your reactions and thoughts can be impaired without you fully being aware of it. Your moods also can change and the slightest thing make you irritable, your children are now also having to deal with your fun night out.
The other issue when using drugs and alcohol is when dealing CYF the fact is, it will not make things better for your case. It will not give you the answers or fix things so you can have them returned to your care. What it can do is create further issues. Parents just days away from having children return can be busted or arrested for drink driving. That one session could steal your loved ones away forever or be the one thing that seals the deal that they go into permanency. You may not be even aware that cyf have changed their minds as sometimes things take time for you to be informed and when you gave up hope and ripped up a good session that one chance is now gone. It may even impact your access in someway and those important visits removed. So is 'that session' still worth it? Is it harmless?
Please if you really want to be a GREAT parent with or without your children in your care seek D&A help and make a change.