If sleep deprivation went on for two or three nights, it would have major effects on how people could operate.
Eleven per cent of new mums suffer severe sleep deprivation, and a third will lose some sleep, a survey has found.
Nearly a fifth of those who took part said they regularly went 24 hours without sleep in the first eight weeks of their baby's life.
Sleep experts believe the answer is for new mums to sleep when their babies do and "catnap" during the day.
Researchers questioned 47 new mums about their sleep. Fewer than a quarter (23%) of those who were missing out managed to catch up.
Those who had fewer than three hours sleep a night can feel out of control the next day.
Fifty-eight per cent said they found it difficult to carry out even simple tasks.
Ninety per cent of those who were getting more than six hours a night described themselves as happy, while 39% of those getting fewer than three hours were unhappy.
End in sight
Sleep psychologist Dr Dieter Wolke, who drew up the research, said: "The experience of cumulative sleep deprivation can affect a person's wellbeing, but the hope that things will get better makes most mums cope."
Dr Heather Engleman, a research fellow at the Edinburgh Sleep Centre, said the research findings fitted in with what was known about how sleep deprivation affected people.
She said sleep influenced moods and patience and often exaggerated problems.
If sleep deprivation went on for two or three nights, it would have major effects on how people could operate.
"They will first observe decrements in performance in with complex tasks. That's where driving comes in.
"Sleep deprivation impairs driving, with performance worse than after drinking alcohol.
"If you were driving at 4am, having had no sleep the night before, you would drive worse than if you were legally intoxicated.
'Forget the housework'
Dr Engleman advised new mums to try to "catnap" in the day, so they can cope with being woken in the middle of the night.
"For new mums who are not working, its entirely appropriate for them to sleep when their baby sleeps in the day. Don't worry about the housework, or the washing up. Your mental health is more important."
But she warned the symptoms of a lack of sleep should not be confused with post-natal depression, where new mothers also want to sleep all the time and feel very lethargic.
If there is any suspicion of this, a doctor or health visitor should be consulted.