Computer shuts down instead of going to sleep

I have a Toshiba Satellite C650D laptop- 64 bit- I upgraded to Windows 10 about a year ago and have not had any issues. The last few days instead of going to sleep it shuts down. I checked the audio and display adapter drivers and they are up-to-date. I also checked the settings and they are ok. The only thing that has changed is I updated Bitdefender to 2017 on Friday and that is when the problem started. I did not have the problem before the update. Any suggestions?