5 year old behaviour

[SarahWB]

HELP.......I am at a complete loss with my 5 year old daughter. Her behaviour has gone downhill over the past month and I don't seem to be able to get thought to her at all. She is laughing when I tell her off, completely ignoring me and being silly all the time (might sound trivial but it is so loud & my 2 year old son is copying everything).
I have tried naughty step, stickers, extra praise for good behaviour & taking away a party but nothing works.
Any advice! X

My 2 are 5 and 3, and have been HORRIBLE recently.
I think it is the heat and over tiredness. We have been really busy recently, and so we've just had a weekend of slobbing. Also been to bed early tonight, but DS2 was still awake when I got back at 8.... DS1 was flat out within seconds of head on pillow tho.
Fingers crossed sleep sorts things out - otherwise, can someone please cancel summer....