Alright. Have a question for my husband

My husband works night shift and has for almost a year now. I'm home due to a high risk pregnancy so I'm able to wake him up in time for work but he ALWAYS gets so frustrated when waking up, getting anywhere from 6-9 hours of sleep. Always falls back asleep. When I worked, he was always late for work and never heard his alarms. Is there a cause for this? I can sleep on 4 hours and still get up to my alarms just fine. We have a baby due in June so, trying to get some help if possible before shes here so he can get up and spend time with her! 🙈