I have been living in this apartment for just over 4 months. When I signed the lease it was with a management company and I was informed the building may be shown to be sold. During the first 4 months the place was shown about 4 times spread through out the 4 months.

Starting on Wed They emailed me saying my apartment will be shown 5 out of the next 6 days and multiple times on some days. On Fri and Sat the time given was between 9:00am and 6:00pm. I emailed the management company asking if the fri and sat showings were an open house or if they could give me some more specific times. I also asked if this was going to be a daily occurrence because I sleep during the day and these showings mean I am losing hours of sleep a day. They emailed me back giving me multiple time frames for fri and sat and saying they will be showing the house as much as they want until it is sold.

Is it unreasonable to show an occupied property 5 days of the week multiple times a day and counting? I am losing hours of sleep and feel like I am a guest in this apartment rather than living in a rented home.

Also, the times that I have been here the last couple days when the people showed up they were not being escorted by an agent. Is it OK that they just give people access to my apartment?

No, you do not have to let unaccompanied strangers into your home. And no the amount of showings is not reasonable. Tell them you are willing to provide reasonable showings to prospective buyers when accompanied by an agent.

Some localities specify in landlord tenant law what is considered 'reasonable' showings in a week, or time ranges for open houses.
If someone lets themselves in without an agent, call the police. They should not even have a key. If they buzz, don't let them in.
I would get proactive about your work/sleep hours and set a schedule and hours that they are allowed to show. Sayyou will stop paying rent if they go outside YOUR hours. Let them evict you if they don't like it.