This is my first attempt at one of these.
1. The exposure is objectively measured evening light exposure in the 3 hours before going to bed.
2. The outcome is gestational diabetes.
The Guardian article does not give information on how gestational diabetes was measured.
The full text/abstract for The association between light exposure before bedtime in pregnancy and the risk of developing gestational diabetes mellitus. (Minjee K et al)March 10, 2023DOI:https://doi.org/10.1016/j.ajogmf.2023.100922 is not accessible through the library or online.
The exposure was measured by wrist-worn actigraphs and a sleep diary. The actigraph measurements could be expanded to include sleep parameters and activity levels.
3. Comparison groups:
- 3 participants who spent about 2.6 hours in dim light;
- 12 participants who spent about 2.2 hours in dim light and
- 16 participants who spent about 1.7 hours in dim light before sleep developed gestational diabetes of the 247 women studied.
Five-fold higher odds of developing gestational diabetes were reported in the group who spent about 1.7 hours in dim light compared to those spending 2.6 hours in dim light before sleep.
4. It is hypothesised that melatonin levels may explain the relationship between exposure and gestational diabetes.
In a future study saliva or urine melatonin measurements could be introduced however the short half-life of melatonin should be kept in mind.
5. Confounders accounted for in the analysis: age, sleep quality and sleep duration, body mass index and daytime light exposure.
Other potential confounders may be the hue of light exposure such as blue, yellow or red light sources. Blue light sources are implicated in sleep disturbance irrespective of the intensity of the light.
Quality of sleep and genetic predisposition to type 2 diabetes are other potential confounders.
6. A large, well-designed randomised controlled trial would remove most of the selection bias and give a better baseline balance of potential confounders (known and undetermined as yet). The period of follow-up needs to be much longer and determined by prognostic factors for gestational diabetes. It is necessary to appoint a data monitoring committee to evaluate the data at predetermined intervals for harm/benefit purposes as this is a vulnerable group of trial participants.
Design:
RCT with an intervention arm with specified light sources to exclude blue light.
A control arm with no intervention. Both arms monitored by actigraphs for the full second trimester.
The primary outcome of gestational diabetes with dose-related light stimulus measurements.
Secondary outcomes could include monitoring of sleep parameters and activity levels monitored in the 3 hours before sleep.
