Cosleeping question

My husband and I are sort of "part-time" cosleepers. Meaning, my almost-4-yr-old starts out in her own bed in her own bedroom at night, but most nights of the week she wakes up at around 3 or 4 AM and comes to our room. She doesn't wake us up, just crawls in the bed with us.

Here's my question. My schedule at work varies. Sometimes I work nights, other times I work days, and when I work days I have to get up VERY early.
This is where the problem comes in. If the alarm clock wakes her up, she's usually UP. Which means her father has to get up too. Which also means that neither one of them is getting the sleep that they need. My daughter gets overtired and cranky (like all of us do when we're overtired.), and my husband gets a sleep deprivation that can become dangerous. He's actually been late to pick her up from his mother's house before because he SAT DOWN for a moment and practically went unconscious for 2 or 3 hours.

We've tried making sure she stays in her room on the days when I have to get up so early, with varying degrees of success. But I also WANT her to feel like she can come into our room when she needs us. I don't want her to feel cut off from us. But there are also health and safety issues at work here, too (my husband could easily get hurt at his job if he's not careful.).

Any suggestions would be welcome.