Leaving 8 year old home alone

So my husband and I are debating about leaving our 8 year old home alone for an hour. 
Tomorrow morning my husband has to leave for work at 4am to get there at 5. He is going in early so he can get off early, workout for an hour, then pick up our boy. 
Well I work from 8am-7pm and don't get a chance to workout in the evenings, so I have to workout in the morning. 
Would it be okay to leave my 8 year old home alone from 5am-6am while he is sleeping?  
I would tell him in advanced 
We have an extra phone I would leave for him 
And my gym is 8 blocks away.  
I says yes, my husband says no. What are your thoughts? 

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