Do Mothers or Fathers Lose More Sleep in the First Year? What a 12-Month Study Found
By Lybadora Editorial Team3 min read
Both, but differently. A 2023 study that tracked 232 couples from pregnancy through 12 months postpartum found fathers slept noticeably fewer minutes at every postpartum check-in, for example, about 15 fewer minutes of measured sleep than mothers at 4 months. Mothers, meanwhile, kept sleeping close to as long but far less continuously: at 4 months their sleep was interrupted enough that only 88.6% of their time in bed was actual sleep, against 96% for fathers, and mothers averaged more than twice as many night wakings as fathers throughout the study.
Explanation
"Who is more tired" is usually argued from impression. A 2023 longitudinal study measured it directly, in the same couples, using both sleep diaries and actigraphy (a wrist-worn movement sensor), from the third trimester of pregnancy through a full year postpartum.
Supporting evidence
Horwitz and colleagues followed 232 couples recruited during pregnancy, with 154 couples still measured at the 12-month mark. Actigraphy-measured sleep duration, by timepoint:
| Timepoint | Mothers | Fathers |
|---|---|---|
| Pregnancy (3rd trimester) | 403.5 min | 399.7 min |
| 4 months postpartum | 399.8 min | 384.5 min |
| 8 months postpartum | 392.1 min | 380.3 min |
| 12 months postpartum | 401.5 min | 382.7 min |
Sleep continuity told a different story. "Sleep percent" (the share of time in bed actually spent asleep) at 4 months: 88.6% for mothers versus 95.96% for fathers. Night wakings were higher for mothers at every timepoint measured, including in pregnancy itself (2.16 actigraphy-measured wakings for mothers versus 1.31 for fathers).
Across the whole study, roughly 70% of mothers and 50% of fathers showed at least subclinical insomnia symptoms at some point.
What the numbers mean
The two parents lost sleep in different currencies. Fathers' totals dropped and stayed lower, a genuine reduction in hours. Mothers' totals stayed closer to their pre-birth baseline, but that time became far more fragmented: falling from over 91% sleep efficiency in pregnancy to under 89% by 4 months, with more than double the night wakings of fathers throughout.
That distinction matters for how each parent's tiredness is likely to be experienced and described. A parent losing hours and a parent losing continuity can both report feeling exhausted, from measurably different underlying patterns, which is part of why sleep-loss comparisons between partners so often talk past each other.
What parents can observe
- Total sleep time, which this study found dropped more for fathers.
- Number of night wakings and time spent awake at night, which fell more heavily on mothers throughout, including before birth.
- How these change together over the year, since the study found both patterns persisted through 12 months rather than resolving quickly.
In a two-caregiver household, logging who handled which nighttime wake-up, not just that "someone" did, is what turns this from an impression into a pattern either parent can actually see.
What may explain a pattern
The study did not directly measure which parent performed each nighttime caregiving task, but its authors note the pattern is consistent with mothers remaining more involved in nighttime care overall, for reasons that include breastfeeding but are not limited to it. A shift in either parent's pattern, a father's total sleep recovering, a mother's continuity improving, is worth reading as a change in who is doing what at night, not only as the baby's sleep maturing.
What parents can do
If sleep loss is a source of tension between partners, it may help to name which currency each of you is actually losing, hours, or unbroken stretches, rather than comparing totals that look similar on paper but come from different patterns. Logging night wake-ups by who handled them is a concrete way to see whether the division matches what both partners assume it is.
Safety considerations
This article summarises group-level research findings and is not a measure of any individual couple's experience. Persistent insomnia, exhaustion that does not improve, or a change in mood alongside sleep loss are worth raising with a healthcare provider, for either parent, rather than treated only as an expected phase.